Comparative outcomes of mechanical and transepithelial PRK on the same excimer laser: A contralateral eye study.

PURPOSE: Compare refractive results between mechanical PRK (mPRK) and transepithelial PRK (tPRK) with WaveLight Allegretto EX500 excimer laser system (Alcon Laboratories, Fort Worth, TX, USA). SETTING: Department of Ophthalmology of the Federal University of Sao Paulo, Brazil. DESIGN: Prospective and randomized study. METHODS: In 151 eyes of 73 patients with astigmatism and myopia, both eyes had similar refraction before surgery, with a maximum of 15-µm difference in ablation who underwent mPRK in one eye and tPRK in the contralateral eye. The mean age of the patients in this study was 31.45 ± 6.97 years (range, 22 to 54 years). RESULTS: A comparison was made with all variables between the two groups, and we found that UDVA and SE were worse in the tPRK group at six months than in the mPRK group. In the mPRK group, there was a higher frequency in the +/- 0.50 range and a lower frequency in the +/- 1.50 range. In the tPRK group, however, there was a lower frequency in the +/- 0.50 range and a higher frequency in the +/- 1.50 range. Concerning gain or loss of lines of sight, there was no association between the two groups (chi-square test, p = 0.887). CONCLUSION: Both mPRK and tPRK appear to have similar safety. However, mPRK was associated with significantly better UDVA and SE six months post-operatively.

Automated Capsular Decompression to Avoid Argentinian Flag Sign in Intumescent Cataract.

Purpose: We describe an alternative automated technique that consists of simultaneous anterior capsule puncture and decompression of the capsular bag by using an insulin needle attached to the aspiration tubing of the phacoemulsification device to prevent the occurrence of the "Argentinian Flag sign" during capsulorhexis in intumescent cataract. Setting: Instituto de Olhos de Assis and Center of Specialties Hoftalmed, located in the state of São Paulo, Brazil. Design: Prospective interventional study. Methods: Eighty-eight eyes of 88 patients with white or intumescent cataracts were included in this study. Routine clear cornea incision, capsule staining with trypan blue, intracameral anesthesia, and ophthalmic viscoelastic device were used before the procedure. A 26-gauge needle was connected to the phacoemulsification aspiration tubing using a double male Luer connector for irrigation, and aspiration was inserted into the anterior chamber through a new paracentesis incision with the bevel facing down. Immediately after insertion, automated aspiration of the liquefied cortex was performed to remove anterior intralenticular material and achieve capsular decompression. Compression of the nucleus with the needle tip was performed to remove any liquefied material trapped between the posterior surface of the nucleus and the posterior capsule. All surgeries were performed using the same phacoemulsification and parameters. The rate of complete continuous capsulorhexis was observed and noted. Results: No complications were observed in any of the cases. A single-stage, continuous, and well-centered capsulorhexis was achieved in 100% of cases. Conclusion: We conclude that a simultaneous puncture and decompression of the capsular bag using an insulin needle attached to the aspiration tubing of the phacoemulsification machine effectively avoided the "Argentinian Flag sign" in intumescent cataract surgery.

A New Methodology for Evaluating the Potential Impact of Residual Refractive Astigmatism in Pseudophakic Patients.

Purpose: To validate a new methodology to evaluate the impact of astigmatism in pseudophakia using an astigmatic defocus curve. Setting: Hospital Oftalmológico de Brasilia, Brazil. Design: Non-randomized cohort study. Methods: For every point of the defocus curve, from -2.00 to +3.00 with 0.50D intervals, visual acuity was assessed with optically induced astigmatism (0.50D, 1.00D and 1.50D at 90 and 180 degrees) in pseudophakic patients implanted with a refractive-enhanced intraocular lens. Results: Twelve patients were analyzed. A statistically significant difference was found between the 90° (ATR) and 180°(WTR) axis with 1.50D astigmatism, providing better visual acuity in ATR astigmatism (p < 0.05). Conclusion: This new methodology is reproducible, useful and may predict residual astigmatism tolerance in pseudophakic patients, which may help with surgery planning and IOL decision-making.

New Device for the Correction of Aphakia Without Capsular Support.

PURPOSE: This study describes a prototype developed for aphakia without capsular support (AWCS) and its proof of concept. METHODS: This descriptive study used a 3D software to create and analyze virtual prototypes before manufacturing. A nylon-6/nylon-6.6 copolymer filament and a 3D printer were used for prototyping. A device implantation technique was developed using a 23-gauge hypodermic needle. Two opposing markings, 2 mm posterior to the limbus, were made to determine the location of the scleral punctures and the final position of the device. After adequate centralization and positioning of the device, its haptics were cut and cauterized to generate thermal modeling of the extremity and allow the thickening of the tips (flange), serving as an anchoring mechanism to the sclera. The efficacy and adequacy of the technique and device were then evaluated. RESULTS: Vitreous tissue extrusion was not observed during the sclerotomy. The device was well fixed to the sclera; however, adequate IOL stability and centralization still needed to be achieved. The surgeon evaluated the adequacy of all the other devices' characteristics. CONCLUSIONS: The development of a technology prototype for correcting AWCS was possible. Although the proposed prototype met most of the established concept guidelines, the stability of the IOL position remains challenging.

Visual rehabilitation after LASIK complication: flap amputation, topo-guided surgery, and phacoemulsification.

We present a case of a patient complaining of monocular diplopia due to a decentered ablation after LASIK. The patient underwent a wavefront-guided retreatment, which resulted in an epithelial ingrowth complication. Additionally, the patient developed cataract, with cataract surgery requiring reliable biometric measurements. Therefore, we opted for corneal treatment and corneal surface regularization. Although we attempted to lift the flap and wash the interface initially, the procedure proved unsuccessful, thereby necessitating immediate flap amputation. Once the corneal surface was regularized in the seventh postoperative month, transepithelial photorefractive keratectomy was successfully performed to homogenize the ocular surface, thereby significantly improving the patient's corrected visual acuity and resolving monocular diplopia. The surface and corneal curvature stabilized by the fifth month after the procedure. Phacoemulsification was then performed along with the implantation of a toric monofocal lens, which was selected using an appropriate formula, resulting in an excellent uncorrected visual acuity.

Ultraviolet-A absorbance analysis in thin porcine corneas pre-and post-crosslinking.

PURPOSE: To determine the absorbance coefficient of the thin porcine cornea to ultraviolet-A radiation (365 nm) submitted for crosslinking. METHODS: This in vitro, benchtop experiment using cadaver tissue study analyzed 12 porcine corneal lamellas, which were obtained using a microkeratome after mechanical de-epithelization and separated into three thickness groups: 180, 300, and 360 µm. The corneal thickness values were measured by anterior-segment optical coherence tomography. All lamellas had ultraviolet-A (365 nm) absorbance measured with a 96-well plate spectrophotometer using an ultraviolet transparent microplate before riboflavin instillation and preand post-crosslinking according to the Dresden protocol. RESULTS: The ultraviolet absorbance profiles of the 180, 300, and 360 µm groups were obtained as α-coefficients of 12.85, 76.55, and 120.27, respectively. A theoretical formula was calculated though a statistical analysis that demonstrated the correlation between stromal lamellar thickness and ultraviolet absorbance. CONCLUSIONS: Corneal thickness and ultraviolet-A spectral absorbance of corneal lamellas showed linear correlation. These findings can potentially contribute to the optimization of ultraviolet-A application during crosslinking, making the treatment of corneas with thickness <400 µm safe and personalized energy delivery for each corneal thickness.

Radial keratotomy: background and how to manage these patients nowadays.

In this review, we presented the principles of radial keratotomy (RK), its evolution, enhancement, and complications, and strategies to manage the consequences of RK in the present day. It is essential to understand the RK procedure f, the theoretical background that supported this surgery, the current effect on the cornea, and how to approach patients needing vision improvement. These patients are developing cataracts that need to be handled well, from the IOL calculation to the surgical procedure. Guided keratorefractive surgery is the most accurate procedure to improve these patient's vision and life. Nevertheless, some patients may need other approaches, such as sutures, penetrating keratoplasty, corneal rings, and pinhole implants, depending on the degree of irregularity of the cornea, ablation depth for guided surgery or if the sutures are open.

Vision-Related Quality of Life in Patients With Keratoconus With Enantiomorphic Topography After Bilateral Intrastromal Corneal Ring Implantation.

PURPOSE: The aim of this study was to evaluate the quality of life (QOL) after intrastromal ring implantation in patients with keratoconus. METHODS: This was a prospective, randomized, interventional study. We analyzed 60 eyes of 30 patients aged 16 to 35 years who were treated at the Department of Ophthalmology and Visual Sciences, Federal University of São Paulo, Brazil. The Visual Function Questionnaire (VFQ-25) and Short-Form 36 Questionnaire (SF-36) were used before intracorneal ring segment (ICRS) implantation and at 3, 6, and 12 months after surgical intervention. RESULTS: The mean corrected visual acuity improved from a mean of 0.32 ± 0.2 logMAR (20/40) preoperatively to 0.14 ± 0.11 logMAR (20/25) 1 year postoperatively ( P = 0.001). The mean spherical equivalent varied from -7.24 ± 3.47 preoperatively to -4.13 ± 2.41 postoperatively ( P = 0.001). The overall composite score for the VFQ-25 improved from 55.1 preoperatively to 80.4 1 postoperatively ( P = 0.001). SF-36 showed statistically significant improvement in all scores. When analyzing the correlation between visual acuity and VFQ composite score, a significant correlation was found between both variables (Pearson correlation coefficient of -0.40, P = 0.001). CONCLUSIONS: Patients with keratoconus had increased psychological symptoms and lower QOL and improved psychosocial criteria associated with corneal remodeling and decreased visual dependence on others after surgery. Extrapolation of these data to the whole keratoconus population suggests that ICRS implantation could improve QOL in these patients.

Ultraviolet-A absorbance analysis in thin porcine corneas pre-and post-crosslinking

ABSTRACT Purpose: To determine the absorbance coefficient of the thin porcine cornea to ultraviolet-A radiation (365 nm) submitted for crosslinking. Methods: This in vitro, benchtop experiment using cadaver tissue study analyzed 12 porcine corneal lamellas, which were obtained using a microkeratome after mechanical de-epithelization and separated into three thickness groups: 180, 300, and 360 μm. The corneal thickness values were measured by anterior-segment optical coherence tomography. All lamellas had ultraviolet-A (365 nm) absorbance measured with a 96-well plate spectrophotometer using an ultraviolet transparent microplate before riboflavin instillation and preand post-crosslinking according to the Dresden protocol. Results: The ultraviolet absorbance profiles of the 180, 300, and 360 μm groups were obtained as α-coefficients of 12.85, 76.55, and 120.27, respectively. A theoretical formula was calculated though a statistical analysis that demonstrated the correlation between stromal lamellar thickness and ultraviolet absorbance. Conclusions: Corneal thickness and ultraviolet-A spectral absorbance of corneal lamellas showed linear correlation. These findings can potentially contribute to the optimization of ultraviolet-A application during crosslinking, making the treatment of corneas with thickness <400 μm safe and personalized energy delivery for each corneal thickness.

Comparison of Pentacam data in patients with diagnostic criteria for keratoconus in only one eye / Comparação dos dados do Pentacam em pacientes com critérios diagnósticos de ceratocone em apenas um olho

ABSTRACT Purpose: To compare data extracted from the Pentacam exam in patients with keratoconus in one eye and form fruste keratoconus in the other eye. Setting: Private clinic in São Paulo, Brazil. Design: Retrospective review. Methods: This study reviewed charts of patients with keratoconus in one eye and forme fruste keratoconus (FFKC) in the other, from January to December 2019. All subjects were evaluated with a rotating Scheimpflug imaging system. Twenty-two eyes of 11 patients were compared, and only one eye had established diagnostic criteria for keratoconus. Given this, 38 variables obtained through Pentacam were compared. Results: In eyes with keratoconus, several parameters exhibit significant alterations compared to those with FFK eyes. Notably, Belin elevation and posterior and total densitometry remain consistently significant, indicating early changes in mild forms of the disease and progression over time. Additionally, indicators such as IVA, KI, IHD, posterior elevation of BFTA, and R min demonstrate notable changes in FFKC eyes. Among these, the index of height decentration (IHD) stands out, with the highest alteration rate of 81.8% in FFKC patients. Furthermore, parameters like the D index (total), EI posterior, and Maximum posterior elevation with BFS, IHD, Kmax, and Q value demonstrate high accuracy, sensitivity, and specificity in distinguishing FFKC from control eyes. Kmax, Belin Ambrósio Posterior Elevation, IHD, and posterior elevation of best-fit reference sphere (BFS Posterior Elevation) emerge as the most altered parameters in FFKC. Conclusion: We considered the IHD, the BFS posterior elevation, Kmax, asphericity, Belin-Ambrósio display, and decentration of the thinnest point as sensitive indicators for initial keratoconus cases, IHD being the most accurate of them.

RESUMO Objetivo: Comparar os dados extraídos do exame Pentacam em pacientes com ceratocone em um olho e ceratocone frusto no outro olho. Local: Clínica privada em São Paulo, Brasil. Desenho do estudo: Revisão retrospectiva. Métodos: Este estudo revisou prontuários de pacientes com ceratocone em um olho e ceratocone forma frusta (FFKC) no outro, de janeiro a dezembro de 2019. Todos os indivíduos foram avaliados com um sistema de imagem Scheimpflug rotativo. Vinte e dois olhos de 11 pacientes foram comparados, e apenas um olho tinha critérios diagnósticos estabelecidos para ceratocone. Diante disso, 38 variáveis obtidas através do Pentacam foram comparadas. Resultados: Em olhos com ceratocone, vários parâmetros apresentam alterações significativas em relação àqueles com olhos FFKC. Notavelmente, a elevação de Belin e a densitometria posterior e total permanecem consistentemente significativas, indicando mudanças precoces nas formas leves da doença e progressão ao longo do tempo. Além disso, indicadores como IVA, KI, IHD, elevação posterior do BFTA e R min demonstram alterações notáveis nos olhos do FFKC. Dentre estes, destaca-se o índice de descentração da altura (IHD), com maior taxa de alteração de 81,8% nos pacientes com FFKC. Além disso, parâmetros como o índice D (total), IE posterior e elevação máxima posterior com BFS, IHD, Kmáx e valor de Q demonstram alta acurácia, sensibilidade e especificidade na distinção entre o FFKC e o olho controle. Kmax, Belin Ambrósio Elevação Posterior, IHD e elevação posterior utilizando BFS (BFS Posterior Elevation) emergem como os parâmetros mais alterados no FFKC. Conclusão: Consideramos o IHD, a elevação posterior com BFS, Kmáx, a asfericidade, o Belin-Ambrósio e a descentração do ponto mais fino como indicadores sensíveis para os casos iniciais de ceratocone, sendo o IHD o mais preciso.

Treatment of irregular astigmatism by topography-guided ablation / Tratamento do astigmatismo irregular por ablação guiada por topografia

ABSTRACT Topography-guided ablation was designed to improve corneal regularity throughout the correction of corneal high order aberrations. The present report described three cases with different indications for topography-guided ablation to correct irregular astigmatism. The patients were monitored in the immediate and late postoperative periods to evaluate long-term corneal stabilization. Surgery indications were based on the patient's complaint of poor quality of vision associated with previous radial keratotomy, corneal transplant, or keratoconus. In all three cases, the patients reported an improvement in the quality of their vision and expressed satisfaction with the procedure; however, the patient who had previously been submitted to crosslinking presented with keratoconus progression in the late postoperative period. Finally, topography-guided customized ablation appears to represent a safe and effective technique for reducing corneal irregularities.

RESUMO A ablação guiada por topografia foi projetada para melhorar a regularidade da córnea durante a correção de aberrações de alta ordem da córnea. O presente relato descreveu três casos com diferentes indicações de ablação guiada por topografia para correção de astigmatismo irregular. Os pacientes foram monitorados no pós-operatório imediato e tardio para avaliar a estabilização corneana em longo prazo. As indicações cirúrgicas basearam-se na queixa do paciente de má qualidade de visão associada a ceratotomia radial prévia, transplante de córnea ou ceratocone. Nos três casos, os pacientes relataram melhora na qualidade da visão e manifestaram satisfação com o procedimento; entretanto, o paciente que já havia sido submetido ao crosslinking apresentou progressão do ceratocone no pós-operatório tardio. Finalmente, a ablação personalizada guiada por topografia parece representar uma técnica segura e eficaz para reduzir irregularidades da córnea em córneas não ectásicas.

Biometric error analysis after cataract surgery performed by residents, in patients with high myopia with SRK/T formula and Wang-Koch formula adjustment / Análise de erros biométricos após cirurgia de catarata realizada por residentes em pacientes com alta miopia com a fórmula SRK/T com ajuste pela fórmula Wang-Koch

ABSTRACT Objective To evaluate intraocular lens power calculation and postoperative refractive errors in patients with high myopia undergoing cataract surgery, comparing predicted target refraction and actual postoperative refraction measured 30 days after surgery with SRK/T formula. Methods This retrospective analysis comprised 39 eyes of 31 patients undergoing cataract surgery through phacoemulsification with in-the-bag IOL implantation. Axial length was measured by partial coherence interferometry or immersion ultrasound biometry, with measurements greater than 26 mm and preoperative myopia greater than -6.0 D Manifest refraction was performed at the 1-month postoperative visit, and the spherical equivalent was analyzed. Results After analysis of 39 eyes of 31 patients undergoing cataract surgery with a mean axial length of 30.4 (standard deviation of 2.2) mm, the mean preoperative refractive spherical equivalent was -15.6 (standard deviation of 7.6) D, ranging from -24.0 to -13.4 D. At 30 days postoperatively, the mean spherical equivalent was -0.35 (standard deviation of 1.1) D, ranging from -2.4 to 2.50 D. Conclusion We encountered a correlation between the absolute refractive error and the dioptric power of the intraocular lens. Against expectations, in our study, ultrasound biometry yielded better results than the optical biometer device, probably due to the small number of patients undergoing optical biometry, suggesting that well-performed immersion biometry can still produce satisfactory results.

RESUMO Objetivo Avaliar os cálculos de potência da lente intraocular e os erros refrativos pós-operatórios em pacientes com alta miopia submetidos à cirurgia de catarata, comparando a refração-alvo prevista e a refração pós-operatória real medida 30 dias após a cirurgia com a fórmula SRK/T. Métodos Esta análise retrospectiva incluiu 39 olhos de 31 pacientes com cirurgia de catarata de facoemulsificação não complicada com implantação de lente intraocular na bolsa. Os comprimentos axiais foram medidos por biometria de coerência óptica ou ultrassônica (imersão), com medidas de axial length (AL) maiores que 26 mm em pacientes com miopia maior que -6.0 D. A refração manifesta foi realizada na consulta pós-operatória de 1 mês, e o equivalente esférico foi analisado. Resultados Após análise de 39 olhos de 31 pacientes submetidos à cirurgia de catarata com AL médio de 30,4 (desvio-padrão de 2,2) mm, o equivalente esférico refrativo médio pré-operatório foi de -15,6 (desvio-padrão de 7,6) D, variando de -24,0 a -13,4 D. Aos 30 dias de pós-operatório, o equivalente esférico médio foi de -0,35 (desvio-padrão de 1,1) D, variando de -2,4 a 2,50 D. Conclusão Encontramos uma correlação entre o erro refrativo absoluto e o poder dióptrico da lente intraocular. Contrariando as expectativas, em nosso estudo, a biometria ultrassônica apresentou melhores resultados que o biômetro óptico, provavelmente devido ao pequeno número de pacientes submetidos à biometria óptica, sugerindo que a biometria de imersão bem executada ainda pode produzir resultados satisfatórios.

Measurement of the visual axis through two different methods: quantification and differences for measuring chord μ / Medição do eixo visual através de dois métodos diferentes: quantificação e diferenças para medição da corda μ

ABSTRACT Purpose: To compare the differences between the apparent and actual chord μ. Methods: In this prospective, comparative, non-randomized, and non-interventional study, imaging examinations using Pentacam and the HD Analyzer were performed in the same room under the same scotopic conditions. The inclusion criteria were patients aged 21-71 years, able to provide informed consent, myopia up to 4D, and anterior topographic astigmatism up to 1D. Patients using contact lenses, those with previous eye diseases or surgeries, corneal opacities, corneal tomographic changes, or suspected keratoconus were excluded. Results: Altogether, 116 eyes of 58 patients were analyzed. The patients' mean age was 30.69 (±7.85) years. In the correlation analyses, Pearson's correlation coefficient of 0.647 indicates a moderate positive linear relationship between apparent and actual chord μ. The mean actual and apparent chord μ were 226.21 ± 128.53 and 278.66 ± 123.90 μm, respectively, with a mean difference of 52.45 μm (p=0.01). The analysis of mean pupillary diameter resulted in 5.76 mm using the HD Analyzer and 3.31 mm using the Pentacam. Conclusions: We found a correlation between the two measurement devices, and even though we found considerable differences, both can be used in daily practice. Given their differences, we should respect their peculiarities as well.

RESUMO Objetivo: Comparar as diferenças entre a chord aparente μ e o chord real μ. Métodos: Estudo prospectivo, comparativo, não randomizado e não intervencionista. Os exames de imagem (Pentacam e HD Analyzer) foram realizados na mesma sala e nas mesmas condições escotópicas. Os critérios de inclusão foram idade de 21 a 71 anos; compreensão do termo de consentimento; miopia até 4D e astigmatismo topográfico anterior até 1D. Os critérios de exclusão foram usuários de lentes de contato; pacientes com doenças oculares prévias ou cirurgias; opacidades da córnea; a presença de alterações tomográficas da córnea ou suspeita de ceratocone. Resultados: Em nosso estudo foram analisados 116 olhos de 58 pacientes. A média de idade foi de 30,69 anos (± 7,85). Análises de correlação foram desenvolvidas e o coeficiente de correlação de Pearson (0,647) indica uma relação linear positiva moderada entre as variáveis. A média do chord μ real foi 226,21 ± 128,53 μm e a média do chord μ média foi 278,66 ± 123,90 μm, com diferença média de 52,45 μm (p=0,01). A análise do diâmetro pupilar médio apresentou: 5,76mm no HD Analyzer e 3,31mm no Pentacam. Conclusões: Entendemos a existência de uma diferença significativa entre os métodos e assim a medida de ambos os dispositivos com base em princípios diferentes devemos respeitar suas peculiaridades. Como encontramos correlação entre as duas medidas, acreditamos que ambas podem ser utilizadas na prática diária.

Visual rehabilitation after LASIK complication: flap amputation, topo-guided surgery, and phacoemulsification

ABSTRACT We present a case of a patient complaining of monocular diplopia due to a decentered ablation after LASIK. The patient underwent a wavefront-guided retreatment, which resulted in an epithelial ingrowth complication. Additionally, the patient developed cataract, with cataract surgery requiring reliable biometric measurements. Therefore, we opted for corneal treatment and corneal surface regularization. Although we attempted to lift the flap and wash the interface initially, the procedure proved unsuccessful, thereby necessitating immediate flap amputation. Once the corneal surface was regularized in the seventh postoperative month, transepithelial photorefractive keratectomy was successfully performed to homogenize the ocular surface, thereby significantly improving the patient's corrected visual acuity and resolving monocular diplopia. The surface and corneal curvature stabilized by the fifth month after the procedure. Phacoemulsification was then performed along with the implantation of a toric monofocal lens, which was selected using an appropriate formula, resulting in an excellent uncorrected visual acuity.

Ten-year follow-up of corneal cross-linking and refractive surface ablation in patients with asymmetric corneal topography.

Purpose: Compare the safety and efficacy of wavefront-guided photorefractive keratotomy (PRK) 6 months after cross-linking (CXL) to wavefront-guided PRK alone for refractive correction in patients with bilateral asymmetric corneal topography. Methods: Prospective randomized clinical trial with 16 patients (32 eyes). CXL with subsequent PRK after 6 months in one eye, and PRK alone was performed in contralateral eyes. The follow-up was 10 years. We analyzed visual outcomes, Scheimpflug topography, and corneal haze evaluation. Results: Eyes in the PRK group showed better results than in the CXL + PRK group. Mean postoperative CDVA was 0.044 logmar (SD, 0.073) in the PRK group and 0.1 logmar (SD, 0.21) in the CXL + PRK group, the mean sphere was + 0.21 (SD, 0.6) D in the PRK group and 0.87 (SD, 2.3) D in the CXL + PRK group, and mean SE was -0.35 (SD, 0.65) D in the PRK group and 0.62 (SD, 2.32) D in the CXL + PRK group. In one patient, a steepening of 2.5 D and a thinning of 17 µm occurred in PRK alone group. Two patients in the CXL + PRK group presented corneal haze. The overall complication rate was 18,75% (haze and ectasia). Conclusion: Non-simultaneous CXL and PRK procedures yielded good refractive results, but worse than those obtained with PRK alone. Although one patient in the PRK group developed corneal ectasia, the CXL + PRK group had a higher loss of vision lines, indicating less safety.

Results of Fibrin Glue Applied Over the Corneal Surface Immediately After Pterygium Surgery: A Novel Pain Relief Technique.

PURPOSE: The aim of this study was to compare the use of fibrin glue on the corneal epitheliectomy site at the end of pterygium surgery versus conventional eye patch regarding pain levels, need for oral analgesic medications, number of days feeling pain, and awakening due to pain after surgery. METHODS: Forty-eight eyes of 24 patients with bilateral primary pterygium were included in this prospective, randomized, double-masked controlled trial. Each eye of the same patient was randomized to the intervention or control group. The intervention group received 2 drops of fibrin glue in the epitheliectomy site at the end of surgery and an eye patch, whereas the control group was only received an eye patch. Patients returned on the first and seventh days after surgery. Pain intensity (measured using the visual pain analog scale), need for oral analgesics, the number of days the pain lasted, and quality of sleep were assessed during follow-up visits and compared between groups. Comparison analysis accounted for sex, age, pterygium grading, and comorbidities. RESULTS: Visual analog pain scale after surgery was significantly lower in eyes receiving fibrin glue (-1.58; 95% confidence interval: -2.84 to -0.32; P = 0.014). In addition, the intervention group presented a 73% lower chance of using oral analgesics (OR: 0.27; 95% confidence interval: 0.07-0.95; P = 0.041). No difference in the awakenings at night was noted ( P = 0.240) nor the mean days of ocular pain in the first week after surgery ( P = 0.474). CONCLUSIONS: Fibrin glue at the end of pterygium surgery effectively reduces pain and the need for oral analgesics compared with conventional eye patching. This study is the first to describe the results of this strategy.

Comparison of endothelial cell loss in diabetic patients after conventional phacoemulsification and femtosecond laser-assisted cataract surgery.

PURPOSE: This study aims to comparatively evaluate the morphological changes of the cornea after phacoemulsification (PHACO) and femtosecond laser-assisted cataract surgery (FLACS) without intercurrences in patients with type 2 diabetes mellitus. METHODS: A total of 95 diabetic patients with moderate cataracts (N2 + and N3+), 47 undergoing PHACO and 48 undergoing FLACS, were selected randomly for the study. Surgeries were performed by a single surgeon between July 2021 and December 2021. Cumulative dissipated energy (CDE) and total balanced saline solution (BSS) data were obtained at the end of each surgery. Changes in corneal endothelial cell density (ECD) and central corneal thickness (CCT) at three months postoperatively were investigated. RESULTS: After three months, evidence is lacking between groups in the CCT measures; the difference was neither statistically nor clinically relevant. However, for ECD, a significant and clinically significant difference was found; if all patients were treated with laser, the mean ECD would be 423.55 greater (RSE: 86.09; p-value < 0.001; 95% CI: 254.81-592.29) than the ECD potential means of 1656.423 among the conventional group (RSE: 74.90; p-value < 0.001; 95% CI: 1509.62-1803.23). CONCLUSIONS: Diabetic patients under treatment with moderate cataracts may predispose themselves to a more significant loss of endothelial cells after conventional phacoemulsification than femtosecond laser-assisted cataract surgery. TRIAL REGISTRATION: It was registered at The Brazilian Registry of Clinical Trials (ReBEC) with the code RBR-6d8whb5 (UTN code: U1111-1277-6020) on 17/05/2022.

Spectrophotometric Analysis of Different Polymethyl Methacrylate Filters and their Importance in the Implantation of Corneal Rings.

PURPOSE: This study evaluated the luminous behavior applied to materials used in intraocular surgeries. METHODS: Discs of the different products were delivered in 19.00 mm × 3.00 mm. Each sample was fixed on support keeping it perpendicular to the spectrophotometer beam. Later, their analyses were carried out in the air/PMMA ratio. The graphs of individual profiles of the measurements along the length were constructed according to each of the filters from the spectrophotometric analysis. In addition, descriptive statistics of transmittance and absorbance for each wavelength presented were correlated for each filter. RESULTS: It is possible to observe that the minimum absorption measure was found in the Red Filter, especially in the blue and green light spectrum. CONCLUSION: Using filters in PMMA materials appears to improve visual quality in corneal implants, especially the red filter, due to greater absorbance of light leading to fewer light scattering phenomena through corneal rings. However, further studies comparing the effects of different filters on Intracorneal rings should be carried out to elucidate this field of study.

Measurement of the visual axis through two different methods: quantification and differences for measuring chord µ.

PURPOSE: To compare the differences between the apparent and actual chord µ. METHODS: In this prospective, comparative, non-randomized, and non-interventional study, imaging examinations using Pentacam and the HD Analyzer were performed in the same room under the same scotopic conditions. The inclusion criteria were patients aged 21-71 years, able to provide informed consent, myopia up to 4D, and anterior topographic astigmatism up to 1D. Patients using contact lenses, those with previous eye diseases or surgeries, corneal opacities, corneal tomographic changes, or suspected keratoconus were excluded. RESULTS: Altogether, 116 eyes of 58 patients were analyzed. The patients' mean age was 30.69 (±7.85) years. In the correlation analyses, Pearson's correlation coefficient of 0.647 indicates a moderate positive linear relationship between apparent and actual chord µ. The mean actual and apparent chord µ were 226.21 ± 128.53 and 278.66 ± 123.90 µm, respectively, with a mean difference of 52.45 µm (p=0.01). The analysis of mean pupillary diameter resulted in 5.76 mm using the HD Analyzer and 3.31 mm using the Pentacam. CONCLUSIONS: We found a correlation between the two measurement devices, and even though we found considerable differences, both can be used in daily practice. Given their differences, we should respect their peculiarities as well.

Unexpectedly high corneal flap thickness and ectasia after mechanical LASIK / Espessura inesperadamente alta do flap corneano e ectasia após LASIK mecânico

ABSTRACT LASIK is a refractive surgical procedure in which a corneal flap is created to expose the corneal stromal bed. Preoperative estimation of corneal flap thickness is necessary to calculate the percentage tissue altered in LASIK, an important quantitative risk factor for ectasia. The objective of this study was to assess flap thickness and calculate percentage tissue altered to check if unexpectedly thicker flaps and higher percentage tissue altered could pose as risk factors of ectasia. Four subjects (eight eyes) were submitted to mechanical LASIK in 2009 and 2010. Pre and postoperative clinical and tomographic data were reviewed. Mean preoperative estimated percentage tissue altered was 39.18±1.31%, which was borderline for increased ectasia risk when considering the limit of 40%. However, when considering the postoperatively measured flap thickness, the actual mean percentage tissue altered turned out to be 45.17 ± 4.13%, which was significantly higher than predicted preoperatively (p=0.002). Unexpectedly higher postoperative percentage tissue altered may be responsible for corneal ectasia after mechanical LASIK.

RESUMO A LASIK é um procedimento cirúrgico refrativo, no qual um retalho corneano é criado para expor o leito estromal corneano. A estimativa pré-operatória da espessura do retalho corneano é necessária para calcular o percentual de tecido alterado no LASIK, um importante fator de risco quantitativo para ectasia. O objetivo deste estudo foi avaliar a espessura do retalho e calcular o percentual de tecido alterado para verificar se retalhos inesperadamente mais espessos e percentuais de tecido alterado mais altos poderiam representar fatores de risco de ectasia. Quatro indivíduos (oito olhos) foram submetidos à LASIK mecânica em 2009 e 2010. Dados clínicos e tomográficos pré e pós-operatórios foram revisados. A média de percentual de tecido alterado pré-operatória estimada foi de 39,18±1,31%, limítrofe para risco aumentado de ectasia quando considerado o limite de 40%. No entanto, ao considerar a espessura do retalho medida no pós-operatório, o percentual de tecido alterado médio real foi de 45,17±4,13%, ou seja, significativamente maior do que o previsto no pré-operatório (p=0,002). O percentual de tecido alterado pós-operatóriao inesperadamente mais alto pode ser responsável pela ectasia da córnea após LASIK mecânico.