Prediction of the small aperture intraocular lens on visual acuity in patients with keratoconus.

PURPOSE: To investigate the impact of corneal higher-order aberrations (HOAs) on predicted corrected distance visual acuity (CDVA) in patients with keratoconus at varying simulated pupil apertures. SETTING: Ophthalmology clinics, Medical University of South Carolina, USA. DESIGN: Retrospective chart review study. METHODS: 56 eyes with keratoconus were examined using Scheimpflug tomography during routine examinations prior to medical intervention. The severity of keratoconus was graded using the Amsler-Krumeich classification. Zernike analysis was used to obtain corneal aberrations using simulated pupil diameters of 6-, 4-, and 2 mm. These data were extrapolated to obtain the total RMS HOAs for a 1.6 mm simulated pupil to evaluate the potential effect of a small aperture intraocular lens. Correlation analysis was used to study the impact and relative contributions of HOAs on CDVA. Convolution of HOAs from OPD-Scan III (NIDEK) provided a clinical method to predict CDVA with different simulated pupil sizes in corneas with irregular astigmatism. RESULTS: There were statistically significant positive correlations between photopic CDVA and the magnitude of total and individual (coma, spherical aberration and trefoil) HOAs in this cohort of keratoconus subjects. A keratoconus case with the small aperture IOL confirms the improvement in vision due to the pinhole effect. CONCLUSIONS: The small aperture IOL is expected to markedly reduce aberrations in keratoconus patients up to Amsler-Krumeich class 4 severity to levels consistent with the levels seen in healthy patients. Convolution of corneal HO aberrations with the ETDRS chart provides a useful simulation of the impact of pinhole optics in aberrated eyes.

EYELID MARGIN DISEASE (BLEPHARITIS AND MEIBOMIAN GLAND DYSFUNCTION): CLINICAL REVIEW OF EVIDENCE-BASED AND EMERGING TREATMENTS.

ABSTRACT: Blepharitis is a common ophthalmic condition with multiple etiologies and no definitive, universal treatment. The treatment modalities for managing lid margin diseases vary depending on the disease's cause, location, and severity. For anterior blepharitis, management options include eyelid hygiene with warm compresses, eyelid scrubs, baby shampoo, and over-the-counter eyelid cleansers. Topical antibiotics and antibiotic-steroid combination drops/ointments for the eye and eyelid may accompany these. For posterior blepharitis/meibomian gland dysfunction (MGD), at-home warm compress or in-office administration of heat therapy/thermal pulsation treatment that aims to clear obstruction in the meibomian glands and restore meibum secretions to maintain a healthy tear film, are recommended. In addition to the above treatment strategies, various other compounds to manage lid margin diseases are in the late stages of development. This review summarizes the available treatment modalities or those in the pipeline for treating blepharitis and MGD.

Tolerance to Induced Astigmatism With a Monofocal Intraocular Lens Designed to Extend the Depth of Focus.

PURPOSE: To determine tolerance to residual astigmatism and visual performance in eyes implanted with a monofocal intraocular lens (IOL) designed to extend the depth of focus (Tecnis Eyhance, DIB00; Johnson & Johnson Vision) compared to eyes implanted with a standard monofocal IOL (Tecnis ZCB00; Johnson & Johnson Vision). METHODS: This prospective, observational study enrolled consecutive patients who underwent routine cataract surgery and implantation of either the DIB00 (n = 20) or ZCB00 (n = 20) IOL. Astigmatic defocus was induced with a plus cylinder from +0.50 to +2.00 diopters (D) in 0.50-D steps for each astigmatic orientation (against-the-rule [ATR], with-the-rule [WTR], and oblique). Outcome measures included the comparison of mean visual acuity at each step of defocus, astigmatic defocus curves, and near and intermediate visual acuity. RESULTS: Eyes implanted with the DIB00 demonstrated greater astigmatic tolerance and were more likely to maintain 20/40 or better visual acuity with up to +2.00 D of induced ATR and oblique astigmatism than the ZCB00 IOLs. The DIB00 group showed 1.3 lines better visual acuity at 2.00 D of ATR astigmatic defocus and 1 line better than the ZCB00 group at 1.50 D of oblique astigmatic defocus. Although the distance visual acuity was comparable, near and intermediate visual acuities (both distance-corrected and uncorrected) were better for the DIB00 IOL than for the standard ZCB00 IOL. CONCLUSIONS: The monofocal IOL designed to extend the depth of focus (DIB00 group) showed greater tolerance to induced astigmatism in ATR and oblique orientations and superior uncorrected and distance-corrected near and intermediate visual acuity than the standard monofocal IOL of the same IOL platform. [J Refract Surg. 2023;39(4):222-228.].

Spectral-Domain OCT Lens Meridian Position as a Metric to Estimate Postoperative Anatomical Lens Position.

PURPOSE: To evaluate the prediction of postoperative anatomical lens position (ALP) using intraoperative spectral-domain optical coherence tomography (SD-OCT) lens anatomy metrics in patients who underwent femtosecond laser-assisted cataract surgery. METHODS: Intraoperative SD-OCT (Catalys; Johnson & Johnson Vision) and postoperative optical biometry (IOLMaster 700; Carl Zeiss Meditec AG) were used to assess anterior segment landmarks, including lens thickness, lens volume, anterior chamber depth, lens meridian position (LMP), and measured ALP. LMP was defined as the distance from the corneal epithelium to the lens equator, and ALP was defined as the distance from the corneal epithelium to the IOL surface. Eyes were divided into groups according to axial length (> 22.5 mm, 22.5 to 24.5 mm, and > 24.5 mm) and IOL type (Tecnis ZCB00 [Johnson & Johnson Vision]; AcrySof SN-60WF [Alcon Laboratories, Inc], or enVista MX60E [Bausch & Lomb]) to further analyze the correlation between LMP and ALP. Theoretical effective lens position was back-calculated using a specific formula. Primary outcome was correlation between postoperative measured ALP and LMP. RESULTS: A total of 97 eyes were included in this study. Linear regression analysis displayed a statistically significant correlation between intraoperative LMP and postoperative ALP (R2 = 0.522; P < .01). No statistically significant correlation was observed between LMP and lens thickness (R2 = 0.039; P = .06) or between ALP and lens thickness (R2 = 0.02; P = .992). The greatest predictor for ALP was LMP (ß = 0.766, P < .001; R2 = 0.523). CONCLUSIONS: Intraoperative SD-OCT-measured LMP correlated better than anterior chamber depth and axial length to postoperative ALP. Further studies are necessary to analyze the impact of preoperative or intraoperative LMP measurements on postoperative refractive outcomes. [J Refract Surg. 2023;39(3):165-170.].

Optimized Artificial Intelligence for Enhanced Ectasia Detection Using Scheimpflug-Based Corneal Tomography and Biomechanical Data.

PURPOSE: To optimize artificial intelligence (AI) algorithms to integrate Scheimpflug-based corneal tomography and biomechanics to enhance ectasia detection. DESIGN: Multicenter cross-sectional case-control retrospective study. METHODS: A total of 3886 unoperated eyes from 3412 patients had Pentacam and Corvis ST (Oculus Optikgeräte GmbH) examinations. The database included 1 eye randomly selected from 1680 normal patients (N) and from 1181 "bilateral" keratoconus (KC) patients, along with 551 normal topography eyes from patients with very asymmetric ectasia (VAE-NT), and their 474 unoperated ectatic (VAE-E) eyes. The current TBIv1 (tomographic-biomechanical index) was tested, and an optimized AI algorithm was developed for augmenting accuracy. RESULTS: The area under the receiver operating characteristic curve (AUC) of the TBIv1 for discriminating clinical ectasia (KC and VAE-E) was 0.999 (98.5% sensitivity; 98.6% specificity [cutoff: 0.5]), and for VAE-NT, 0.899 (76% sensitivity; 89.1% specificity [cutoff: 0.29]). A novel random forest algorithm (TBIv2), developed with 18 features in 156 trees using 10-fold cross-validation, had a significantly higher AUC (0.945; DeLong, P < .0001) for detecting VAE-NT (84.4% sensitivity and 90.1% specificity; cutoff: 0.43; DeLong, P < .0001) and a similar AUC for clinical ectasia (0.999; DeLong, P = .818; 98.7% sensitivity; 99.2% specificity [cutoff: 0.8]). Considering all cases, the TBIv2 had a higher AUC (0.985) than TBIv1 (0.974; DeLong, P < .0001). CONCLUSIONS: AI optimization to integrate Scheimpflug-based corneal tomography and biomechanical assessments augments accuracy for ectasia detection, characterizing ectasia susceptibility in the diverse VAE-NT group. Some patients with VAE may have true unilateral ectasia. Machine learning considering additional data, including epithelial thickness or other parameters from multimodal refractive imaging, will continuously enhance accuracy. NOTE: Publication of this article is sponsored by the American Ophthalmological Society.

Scheimpflug-Derived Corneal Lower and Higher Order Aberrations Post Intrastromal Corneal Ring Segments for Keratoconus.

Intrastromal corneal ring segments (ICRS) improve corneal topographic symmetry and reduce corneal aberrations through regularization of the corneal surface, thereby functioning as a viable surgical intervention for patients with keratoconus. This study aims to evaluate changes in lower- (LOAs) and higher-order aberrations (HOAs) amongst varying pupil sizes pre- and post- ICRS implantation in keratoconus patients. We specifically investigate the impact of pupil size on total corneal HOAs up to the 6th order. Twenty-one eyes that underwent ICRS implantation were included in this prospective interventional study. LOAs and HOAs measurements at the 6 mm, 4 mm, and 2 mm pupil diameters were collected preoperatively and at 6 months postoperatively using the Zernicke analysis function on a Scheimpflug device. ICRS implantation demonstrated a statistically significant effect in vertical coma with a −0.23 reduction (p = 0.015) for a 4 mm pupil size and a −1.384 reduction (p < 0.001) for 6 mm, with no significant effect at 2 mm. Horizontal coma, astigmatism 0°, astigmatism 45°, trefoil 5th order 30°, and RMS HOA demonstrated significant reductions at 4 mm or 6 mm pupil sizes but not at 2 mm. Our analysis demonstrates a favorable effect of ICRS implantation on larger pupil sizes, suggesting the importance of pupil size as it correlates with HOAs reduction.

Ray-tracing Analysis of Accommodation and Pseudoaccommodation in Phakic and Pseudophakic Eyes.

PURPOSE: To compare objective measurements of accommodation and pseudoaccommodation in phakic and pseudo-phakic eyes using ray-tracing aberrometry. METHODS: Patients with normal and hyperprolate corneas (post-hyperopic laser in situ keratomileusis) who underwent cataract surgery from March 2018 to October 2019 at the Medical University of South Carolina were examined and received either a diffractive intraocular lens (IOL) with an echelette design (Tecnis ZXR00 Symfony; Johnson & Johnson Vision), a monofocal IOL with negative spherical aberration (Tecnis ZCB00; Johnson & Johnson Vision), or an aberration-free IOL (MX60E; Bausch & Lomb). The control groups consisted of young and presbyopic phakic patients. Ray-tracing wavefront analysis was performed 1 to 3 months postoperatively. Objective ray-tracing metrics of accommodation and pseudoaccommodation included the effective range of focus, sphere shift accommodation, and depth of focus. RESULTS: Sixty-two eyes received a Tecnis ZCB00, 39 a MX60E, and 43 a Tecnic ZXR00 Symfony IOL; furthermore, 20 young phakic eyes and 19 presbyopic eyes were included in this study. The effective range of focus and sphere shift accommodation in the young control group were statistically larger than in the presbyopic group (P = .005 and P < .001, respectively). There was no difference in effective range of focus, sphere shift accommodation, and pseudoaccommodations between the different IOL groups. The young control group had the highest visual Strehl optical transfer function for near and distant targets (0.64 ± 0.24 and 0.56 ± 0.19, respectively), whereas the aberration-free IOL in the MX60E hyperprolate cornea group presented the lowest visual Strehl optical transfer function value for near (0.49 ± 0.19). CONCLUSIONS: Ray-tracing aberrometry can objectively assess accommodative amplitude in phakic eyes and pseudoaccommodation (depth of focus) in pseudophakic eyes. [J Refract Surg. 2022;38(10):661-667.].

Anterior segment reconstruction due to cosmetic iris implants placed in the anterior chamber.

A 27-year-old woman had BrightOcular iris implants placed for cosmetic purposes that changed eye color from brown to blue bilaterally. Of note, BrightOcular implants are not approved by the U.S. Food and Drug Administration (FDA) for use in the United States and have been associated with severe ocular complications. In keeping with their design, they were placed in the anterior chamber (AC) in both eyes of this patient; surgery was performed outside the United States. As has been described previously and tragically in other cases, she developed chronic inflammation, intolerable glare, angle-closure glaucoma, corneal edema, and cataracts in both eyes. For medically unmanageable elevated intraocular pressure (IOP), she underwent diode laser cyclophotocoagulation (CPC) in both eyes, and eventually, an Ahmed tube shunt (New World Medical, Inc.) was placed in the right eye. Although she was advised and urged to have the iris implants removed, despite her ocular issues, she refused removal until intolerable glare and reduced vision ensued. Ultimately, both iris implants were extracted 5 years after implantation by a U.S. surgeon; the procedures resulted in corneal decompensation and progressive cataract development. Subsequent penetrating keratoplasty (PKP) was performed for the right eye, but it failed because of contact with the glaucoma tube shunt. She sought additional consultation and presented with the following findings: corrected distance visual acuity was 20/400 in the right eye and 20/40 in the left eye, IOP of 18 mm Hg in the right eye and 16 mm Hg in the left eye, pupils were nonreactive and fixed, and extraocular muscles and central visual field were normal. Pachymetry was 868 µm in the right eye and 653 µm in the left eye. Anterior segment examination in the right eye revealed a failed corneal graft with 3+ edema, peripheral anterior synechiae (PAS) for 360 degrees, shallow AC, Ahmed tube shunt at the 11 o'clock position and remnant iris adherent to the graft-host junction for 270 degrees, 3+ posterior subcapsular cataract, and 2+ cortical cataract (Figure 1JOURNAL/jcrs/04.03/02158034-202208000-00024/figure1/v/2022-08-01T210317Z/r/image-tiff). The sclera revealed multiple circular and circumferential atrophic blue spots consistent with high-energy transscleral CPC (Figure 2JOURNAL/jcrs/04.03/02158034-202208000-00024/figure2/v/2022-08-01T210317Z/r/image-tiff). In the left eye, she had remnant fixed dilated iris for 270 degrees, missing iris superiorly for 3 clock hours, an adequate AC, and 2+ cortical cataract (Figure 3JOURNAL/jcrs/04.03/02158034-202208000-00024/figure3/v/2022-08-01T210317Z/r/image-tiff). Posterior segment examination revealed a 0.5 cup-to-disc ratio in both eyes with normal vessels, macula, vitreous, and retinal periphery, bilaterally. Given this constellation of findings, how would you proceed?

Impact of the COVID-19 Pandemic on Refractive Surgery.

PURPOSE OF REVIEW: In this article, we review the impact of the COVID-19 pandemic on refractive surgery. RECENT FINDINGS: COVID-19 infection frequently causes eye symptoms, most commonly conjunctivitis or mild irritation. While virus can be detected in tears of symptomatic patients, the risk of transmission via this route appears low. SUMMARY: Refractive surgery consultations were significantly reduced during the pandemic; however, volume is rebounding quickly likely due to a number of lifestyle, health, and financial factors. Laser refractive and intraocular surgery likely confer a low risk of virus spread, especially in asymptomatic patients. Screening prior to the refractive consultation and surface disinfection in the clinic and operating room can help reduce transmission risk further.

Refractive Accuracy of Barrett True-K vs Intraoperative Aberrometry for IOL Power Calculation in Post-Corneal Refractive Surgery Eyes.

PURPOSE: To compare the refractive predictability of intraoperative aberrometry (IA, ORA, Alcon) and Barrett True-K/Universal II formulas for intraocular lens (IOL) power calculations in post-corneal refractive surgery and normal eyes. METHODS: Retrospective study of normal and post-corneal refractive surgery eyes that underwent cataract surgery with IA at tertiary academic center. Preoperatively, IOL power calculations were performed using Barrett Universal II (normal eyes) or Barrett True-K (post-corneal refractive surgery eyes) formulas. Intraoperatively, aphakic IA measurements were used for IOL power calculations. Mean absolute refractive prediction error (MAE) and the percentage of eyes with prediction error within ±0.50, ±0.75 and ±1.00 D were calculated. Refractive predictability was also evaluated in short, normal, and long eyes. RESULTS: Two hundred and seventy-three eyes were included in the analysis. No statistically significant differences were observed between the MAE of preoperative formulas and IA for post-hyperopic laser vision correction (LVC), post-myopic LVC, post-radial keratotomy (RK) and normal eyes. For prediction error within ±0.5 D in post-corneal refractive surgery eyes, range of agreement between Barrett True-K and IA ranged from 28% (7/25) of the time in post-RK eyes to 49% (40/81) of the time in post-hyperopic LVC; the corresponding value for Barrett Universal II/IA was 62% (64/103) in normal eyes. When there was disagreement, IA outperformed Barrett True-K in post-hyperopic LVC eyes and Barrett formula outperformed IA in post-myopic LVC, post-RK, and normal eyes. CONCLUSION: IA appears to be comparable to Barrett formulas for IOL power calculations in post-corneal refractive surgery and normal eyes. In post-hyperopic LVC, IA yields better results compared to Barrett True-K formula; in real-life scenarios, IA reveals statistical advantage over the Barrett True-K no history formula for eyes post-hyperopic LVC.

The corneal endothelium: clinical review of endothelial cell health and function.

The endothelial cell is a critical structure within the cornea and is responsible for maintaining corneal clarity through its pump function. Endothelial cells are lost over time naturally but can be injured medically, surgically, or as a part of various dystrophies. Monitoring of endothelial cells can be performed clinically or more formally with specular microscopy. In cases of significant compromise, endothelial cells can be transplanted by various endothelial keratoplasty techniques. The future pipeline is bright for possible endothelial cell regeneration and rehabilitation. This article reviews these topics in depth to provide a comprehensive look at the structure and function of the endothelial cell, etiologies of endothelial cell damage, detailed review of iatrogenic causes of endothelial cell loss, and management strategies.

Future Trends in Presbyopia Correction.

Presbyopia affects 1.8 billion people worldwide. This reduction in distance corrected near visual acuity impacts quality of life, which prompts patients to seek treatment. Presbyopia is an early manifestation of the "crystalline lens optical dysfunction through aging," or dysfunctional lens syndrome, and appropriate management of presbyopia is dependent on coexisting factors such as increased higher order aberrations, reduced contrast sensitivity, light scatter, and lenticular opacification. This review of published literature (PubMed and MEDLINE) is presented in narrative format and discusses medical and surgical treatments available to patients who experience presbyopia, while highlighting future therapies. Numerous strategies exist for the management of presbyopia. These strategies include pharmacological therapy, glasses and contact lenses, corneal, scleral, and lenticular procedures. This article discusses the role of several new and existing presbyopia treatments, as well as which patients are candidates for these novel therapies. Although no single treatment is ideal for all patients with presbyopia, new medical and surgical strategies increase the number of options available when addressing different stages of presbyopia and dysfunctional lens syndrome. [J Refract Surg. 2021;37(6 Suppl):S28-S34.].

Clinical Validation of the Automated Characterization of Cone Size and Center in Keratoconic Corneas.

PURPOSE: To evaluate an automated method for detecting the cone shape characteristics and to assess the cornea specialists' subjective variability of these measures using different maps. METHODS: Topographic images of the anterior and posterior surface of each eye were presented to 12 clinicians in two different types of map: tangential curvature and relative elevation to the best-fit sphere. They were asked to mark the cone center and its boundaries in the two maps without knowing that they belonged to the same patient. The results between the maps were compared to assess the subjective variability dependent on the map type and the automated method was compared against both estimations to assess its accuracy. RESULTS: Considering the results of anterior and posterior surfaces, there was low agreement between the cone center estimations using different types of maps for 10 of the 12 cases (P < .05), whereas the comparison between the automated method and the two map estimations did not show differences in 11 of the 12 cases (P > .05). There was high variability, up to 55%, among clinicians' estimations of the cone area. The results of the automated method were within the range of the expert's estimations. CONCLUSIONS: An objective, mathematically derived method of determining morphological dimensions of the cone was consistent with clinicians' evaluations. Although there was high variability among the experts' subjective estimates, which were highly influenced by the type of map, the objective method provided a reliable evaluation of the keratoconus shape independent of maps or color scale. [J Refract Surg. 2021;37(6):414-421.].

Neurotrophic keratitis after penetrating keratoplasty for lattice dystrophy.

PURPOSE: To report clinical outcomes of a patient with unilateral neurotrophic keratitis following penetrating keratoplasty for lattice dystrophy treated with topical recombinant human nerve growth factor. OBSERVATIONS: A 75-year-old male with lattice dystrophy and history of herpes simplex keratitis, presented with recurrent neurotrophic ulceration in the right eye two years following penetrating keratoplasty. The patient was successfully treated with topical recombinant human nerve growth factor. CONCLUSION: Neurotrophic keratitis is a rare chronic disorder that affects quality of life due to the risk of vision loss. Topical recombinant human nerve growth factor is a novel and effective treatment option that may help improve optical quality and patient's satisfaction as shown in this case of recurrent neurotrophic keratitis.

Depth- and direction-dependent changes in solute transport following cross-linking with riboflavin and UVA light in ex vivo porcine cornea.

Diffusion is an important mechanism of transport for nutrients and drugs throughout the avascular corneal stroma. The purpose of this study was to investigate the depth- and direction-dependent changes in stromal transport properties and their relationship to changes in collagen structure following ultraviolet A (UVA)-riboflavin induced corneal collagen cross-linking (CXL). After cross-linking in ex vivo porcine eyes, fluorescence recovery after photobleaching (FRAP) was performed to measure fluorescein diffusion in the nasal-temporal (NT) and anterior-posterior (AP) directions at corneal depths of 100, 200, and 300 µm. Second harmonic generation (SHG) imaging was also performed at these three corneal depths to quantify fiber alignment. For additional confirmation, an electrical conductivity method was employed to quantify ion permeability in the AP direction in corneal buttons and immunohistochemistry (IHC) was used to image collagen structure. Cross-linked corneas were compared to a control treatment that received the riboflavin solution without UVA light (SHAM). The results of FRAP revealed that fluorescein diffusivity decreased from 23.39 ± 11.60 µm2/s in the SHAM group to 19.87 ± 10.10 µm2/s in the CXL group. This change was dependent on depth and direction: the decrease was more pronounced in the 100 µm depth (P = 0.0005) and AP direction (P = 0.001) when compared to the effect in deeper locations and in the NT direction, respectively. Conductivity experiments confirmed a decrease in solute transport in the AP direction (P < 0.0001). FRAP also detected diffusional anisotropy in the porcine cornea: the fluorescein diffusivity in the NT direction was higher than the diffusivity in the AP direction. This anisotropy was increased following CXL treatment. Both SHG and IHC revealed a qualitative decrease in collagen crimping following CXL. Analysis of SHG images revealed an increase in coherency in the anterior 200 µm of CXL treated corneas when compared to SHAM treated corneas (P < 0.01). In conclusion, CXL results in a decrease in stromal solute transport, and this decrease is concentrated in the most anterior region and AP direction. Solute transport in the porcine cornea is anisotropic, and an increase in anisotropy with CXL may be explained by a decrease in collagen crimping.

Correlation of Intraoperative Optical Coherence Tomography of Crystalline Lens Diameter, Thickness, and Volume with Biometry and Age.

PURPOSE: To characterize crystalline lens dimensions derived from in vivo spectral-domain optical coherence tomography (SD-OCT) and identify associations among these parameters, ocular biometry, and age. METHODS: In this retrospective study, lens thickness (LT), lens diameter (LD), and lens volume (LV) were measured intraoperatively using SD-OCT in 293 eyes undergoing lens surgery. Correlations among LT, LD, LV, age, axial length (AL), and anterior chamber depth (ACD) were analyzed. Multiple regression analysis was performed to determine whether a combination of biometric data could predict LD and LV. RESULTS: Wide variations were observed in LT (3.6-5.7 mm), LD (7.5-11.9 mm), and LV (119.9-312.4 mm3) of aging eyes. Correlations among the 3 lens dimensions were statistically significant (LV-LT: r = 0.785; P < .001; LV-LD: r = 0.696; P < .001; and LT-LD: r = 0.121; P = .039). With age, the correlation coefficients of LT, LD, and LV were 0.526, 0.326, and 0.573, respectively (P < .001). Although there was significant correlation of AL with LT (r = -0.137; P = .002) and LD (r = 0.268; P < .001), it was not significant with LV (r = 0.084; P = .15). Subgroup analysis revealed that 19.8% of long eyes had LD >1 standard deviation (SD) above and that 5.2% had LD <1 SD below the mean LD. CONCLUSIONS: Dimensions of the aging lens vary considerably and are most accurately characterized by direct measurement of LT, LD, and LV, rather than making assumptions based on AL. These findings challenge historically proposed relationships between LD and AL and represent a normative dataset of contemporary geometric features of the aging lens, possibly aiding in surgical decision making and future developments in lens surgery.

Femtosecond Lasers in Cornea & Refractive Surgery.

Since the introduction of femtosecond laser (FS) systems for corneal flap creation in laser-assisted in-situ keratomileusis there have been numerous applications for FS laser in corneal surgery. This manuscript details the utility of FS lasers in corneal surgical procedures including refractive laser surgeries, intracorneal ring segment tunnels, presbyopic treatments, and FS-assisted keratoplasty. We also review the role of FS lasers in diagnostic procedures such as two photon excitation fluorescence and second harmonic generation.

Dysfunctional lens syndrome: a prospective review / Síndrome do cristalino disfuncional: uma revisão prospectiva

ABSTRACT The term dysfunctional lens syndrome has gained acceptance in the field and encompasses natural changes due to aging of crystalline lens. The evolution of diagnostic devices has been a key factor in better staging, understanding and characterizing of these degenerative changes. Even with these technological advances and the use of subjective classifications, such as the classic Lens Opacities Classification System, an objective staging of early dysfunctional lens syndrome has yet to be established. Ocular wavefront aberrometry and objective scatter index, associated with Scheimpflug backscatter densitometry, have proven instrumental in detecting early dysfunctional lens syndrome. Staging of early dysfunctional lens syndrome has been proposed in the literature, but no classification has been recognized worldwide. The purpose of this literature review is to assess the current state of dysfunctional lens syndrome from a technological perspective and propose a new staging system to assist surgeons in making surgical decisions.

RESUMO O termo "síndrome disfuncional do cristalino" tem sido mais aceito na área e engloba mudanças naturais devido ao envelhecimento do cristalino. A evolução dos dispositivos diagnósticos tem sido fator fundamental para melhor estadiamento, compreensão e caracterização dessas alterações. Mesmo com esses avanços tecnológicos e o uso de classificações subjetivas, como o Lens Opacities Classification System , um estadiamento objetivo da síndrome disfuncional do cristalino precoce ainda não foi estabelecido. A aberrometria ocular total e o índice de superfície ocular, associado à densitometria de Scheimpflug, mostraram-se instrumentais na detecção da síndrome disfuncional do cristalino precoce. Embora estadiamentos precoces de síndrome disfuncional do cristalino tenham sido propostos na literatura, nenhum foi reconhecido mundialmente até o momento. O objetivo desta revisão de literatura é avaliar o estado atual da síndrome disfuncional do cristalino a partir de uma perspectiva tecnológica, e propor um novo sistema de estadiamento para auxiliar os cirurgiões na tomada de decisões cirúrgicas.