Clinical Outcomes of Stage 2 (Pivotal) Use of a Modified Keratoprosthesis Device (ORC-KPro) in Patients with End-stage Corneal Blindness.

Purpose: To investigate the short-term results and performance of a modified Boston keratoprosthesis device manufactured by the Ophthalmic Research Center (ORC-KPro) in patients with end-stage corneal blindness. Methods: This prospective interventional case series was conducted on patients with corneal blindness who were candidates for KPro. The inclusion criterion comprised patients with a best-corrected visual acuity (BCVA) of less than 20/200 in both eyes, in whom the main reason for vision loss was corneal pathology. The ORC-KPro was implanted using the method previously described for Boston KPro. Results: This study focused on 12 eyes of 12 patients with an average age of 45.9 ± 16.8 (range, 19 to 70) years. Eleven patients were male. The KPro indication was corneal blindness due to chemical burns in nine patients (75%) and failure of multiple previous corneal grafts in three patients (25%). Anatomical success was achieved in all patients. The preoperative BCVA was light perception (LP) in 10 eyes and hand motion in 1 eye. Except for one patient who was diagnosed with grade C proliferative vitreoretinopathy during the surgery, the vision of all other patients (91.6%) improved after surgery. The retroprosthetic membrane (RPM) was formed in two eyes (18.1%) after six months. Of the 12 patients, 10 (83.3%) were under treatment with two antiglaucoma medications before surgery. The intraocular pressure of three eyes (25%) was estimated to be high by tactile palpation; however, it decreased in two eyes to the acceptable range. One patient underwent retinal surgery due to total retinal detachment, and two patients (16.7%) underwent vitrectomy due to endophthalmitis. Conclusion: The current study showed that, in the short term, the use of ORC-KPro achieved favorable anatomical success in patients with corneal blindness. However, the functional success rate was limited by the low visual potential due to advanced glaucoma in most patients.

Cutting Edge: Corneal Stromal Lenticule Implantation (Corneal Stromal Augmentation) for Ectatic Disorders.

ABSTRACT: The ectatic disease of the cornea poses a significant challenge for ophthalmologists because commonly used treatments to improve visual acuity, such as spectacles and contact lenses, may not be effective, especially in advanced stages. In addition, the preferred surgical management, corneal transplantation, has various issues related to tissue availability, the steep learning curve, and postoperative complications such as tissue stability and half-life. Ongoing research for an alternative to keratoplasty has suggested various methods, such as corneal crosslinking, which can improve visual function when combined with other techniques. Early reports have become available on the feasibility and safety of different strategies for corneal stromal augmentation, both with and without corneal crosslinking, and their favorable clinical outcomes, including visual and keratometry improvements. Here, we explore the cutting-edge advancements in stromal lenticule implantation, encompassing different facets of the procedure.

A Modified Formula for Intraocular Lens Power Calculation Based on Aphakic Refraction in a Pediatric Population.

Purpose: To investigate and optimize the accuracy of aphakic refraction (AR) techniques for secondary intraocular lens (IOL) power calculation in aphakic children. Methods: Thirty-three aphakic eyes of 18 patients who were candidates for secondary IOL implantation were enrolled in the present study. Axial length (AL) measured by optical biometry was used in the biometric formula (SRK-T, Holladay II, and Hoffer-Q). AR and spherical equivalent (SE) were used in two AR-based formulas (Ianchulev, Leccissotti). True power was calculated based on postoperative SE at three months' follow-up. Results: Regarding the postoperative SE, 13 (40%) eyes were within ± 1.00 diopters (D) and 22 (66%) were within ± 2.00 D. Median absolute error (MedAE) was predicted to be 4.4 and 7.3 D with the use of Ianchulev and Leccissotti formulas, respectively. The corresponding value was 0.8 D with the biometric formula. All eyes were deemed to have myopic refraction when using the AR-based formulas except one eye with the Ianchulev formula. The coefficient of our modified formula was 1.7 instead of 2.01 in the Ianchulev formula. MedAE with the use of new formulae was 0.5 D and was comparable with the true IOL power (P = 0.22). Conclusion: Both Ianchulev and Leccissotti formulas resulted in a significant myopic surprise in aphakic children aged between 4.5 and 14 years. The modified formula proved to determine a more accurate SE that is comparable with biometric formulas.

Long-Term Clinical Outcomes of Keratolimbal Allograft Alone or in Combination With Keratoplasty in Chronic and Delayed-Onset Mustard Gas Keratopathy.

PURPOSE: The purpose of this study was to investigate the long-term clinical outcome of keratolimbal allograft (KLAL) alone or in combination with keratoplasty, in the management of patients with chronic and delayed-onset mustard gas keratopathy (MGK). METHODS: Patients who had KLAL for MGK with or without corneal transplantation between 2002 and 2016 were recalled to be enrolled in this retrospective interventional case series. The primary outcome was the success rate of the KLAL demonstrated by Kaplan-Meier cumulative survival analysis. The secondary outcomes were postoperative BCVA and the need for further surgery. RESULTS: A total of 108 eyes of 68 patients with MGK underwent KLAL. All patients were male with an average age of 54 ± 6 years with an average follow-up duration of 81.9 ± 38.4 months. Sectoral KLAL alone was performed in 62 eyes (57.4%), combined with lamellar keratoplasty (LKP) in 40 eyes (37%) and combined with penetrating keratoplasty in 6 eyes (5.6%). The cumulative probability of success was 75% within the follow-up duration. The mean duration of successful KLAL survival was 80.6 ± 38 months. 88.1% of these eyes needed only 1 operation to stabilize the ocular surface. Average BCVA did not improve significantly after KLAL alone, except in those accompanied by keratoplasty. KLAL combined with LKP achieved the superior clinical outcome compared with KLAL alone. Infectious keratitis occurred in 6 eyes (5.5%). No adverse event due to postoperative systemic immunosuppression was observed. CONCLUSIONS: KLAL alone or combined with LKP is effective, durable, and visually acceptable in the reconstruction of ocular surface in patients with limbal stem cell deficiency secondary to MGK.

Femtosecond Laser-assisted Allogenic Additive Stromal Keratoplasty With or Without Excimer Laser Donor Keratomileusis for Management of Keratoconus.

We describe a modified allogenic intrastromal lenticule implantation technique for management of keratoconus (KCN). Patients with advanced KCN already scheduled for corneal transplantation were enrolled. An allogenic corneal lenticule was implanted inside a stromal pocket created by femtosecond laser. In three cases, the estimated refractive error of the recipient eyes was corrected on the donor lenticules using an Excimer laser. All operated eyes underwent corneal crosslinking at the time of surgery. This method was named "Femtosecond Laser-assisted Allogenic Stromal Keratoplasty Without and With Excimer Laser-assisted Donor Keratomileusis"; briefly called FASK and FASK Plus EDK, respectively. Two out of five patients were satisfied with the results. There was a decrease in the average simulated keratometric values as well as myopia when FASK Plus EDK was performed. Increased corneal thickness was achieved in all cases. Graft edema gradually decreased over weeks but interface wrinkling and lenticule folds in the visual axis remained as a problem during follow-up period. No other complications were encountered.

Secondary Piggyback Intraocular Lens for Management of Residual Ametropia after Cataract Surgery.

PURPOSE: To investigate the indications, clinical outcomes, and complications of secondary piggyback intraocular lens (IOL) implantation for correcting residual refractive error after cataract surgery. METHODS: In this prospective interventional case series, patients who had residual refractive error after cataract surgery and were candidates for secondary piggyback IOL implantation between June 2015 and September 2018 were included. All eyes underwent secondary IOL implantation with the piggyback technique in the ciliary sulcus. The types of IOLs included Sulcoflex and three-piece foldable acrylic lenses. Patients were followed-up for at least one year. RESULTS: Eleven patients were included. Seven patients had hyperopic ametropia, and four patients had residual myopia after cataract surgery. The preoperative mean of absolute residual refractive error was 7.20 ± 7.92, which reached 0.42 ± 1.26 postoperatively (P < 0.001). The postoperative spherical equivalent was within ± 1 diopter of target refraction in all patients. The average preoperative uncorrected distance visual acuity was 1.13 ± 0.35 LogMAR, which significantly improved to 0.41 ± 0.24 LogMAR postoperatively (P = 0.008). There were no intra- or postoperative complications during the 22.4 ± 9.5 months of follow-up. CONCLUSION: Secondary piggyback IOL implantation is an effective and safe technique for the correction of residual ametropia following cataract surgery. Three-piece IOLs can be safely placed as secondary piggyback IOLs in situations where specifically designed IOLs are not available.

Topical 0.03% tacrolimus versus systemic mycophenolate mofetil as adjuncts to systemic corticosteroids for preventing graft rejection after repeat keratoplasty: one-year results of a randomized clinical trial.

PURPOSE: To compare the efficacy of topical 0.03% tacrolimus in combination with systemic corticosteroids versus systemic mycophenolate mofetil (MMF) and corticosteroids in preventing corneal allograft rejection after repeat keratoplasty. METHODS: This prospective, randomized clinical trial enrolled 63 consecutive eyes of 63 patients who underwent repeat keratoplasty after a failed penetrating keratoplasty. Group 1 (32 eyes) received MMF orally 1 g twice daily for the first 6 months and then 1 g daily for the next 6 months, and group 2 (31 eyes) received topical 0.03% tacrolimus four times a day for 12 months. All patients were treated with topical and oral corticosteroids postoperatively. The participants were observed closely for signs of graft rejection, and the rates of rejection-free graft survival were calculated and compared between the two groups at postoperative month 12. RESULTS: The groups were balanced in patient's age and risk factors for graft rejection (e.g., original diagnosis, number of previous grafts, and quadrants of corneal vascularization). Endothelial graft rejection occurred in 5 eyes (15.6%) of group 1 and 6 eyes (19.4%) of group 2 (P = 0.75). Irreversible endothelial graft rejection resulting in graft failure occurred in 3 eyes of each group (P = 0.99). The rate of rejection-free graft survival was 84.4% in group 1 and 80.6% in group 2 at postoperative month 12 (P = 0.74). CONCLUSION: Topical 0.03% tacrolimus was as effective as systemic MMF as adjuncts to topical and systemic corticosteroids in reducing endothelial graft rejection with 12 months follow up after repeat keratoplasty.

Aloe Vera Gel-derived Eye Drops for Alkaline Corneal Injury in a Rabbit Model.

PURPOSE: To investigate the efficacy of topical Aloe Vera (AV) gel-derived eye drops on the healing of alkali-burned corneas in rabbits. METHODS: Thirty alkali-burned corneas of 30 New Zealand albino rabbits were categorized into three groups: AV treatment group that received AV gel-derived eye drops four times a day; medical therapy (MT) group that received conventional treatment; and the control group. Clinical examinations together with digital imaging of the corneas were performed on days 0, 1, 2, 4, and 7. The area of the corneal epithelial defect (CED) was measured using ImageJ software. After euthanizing the rabbits, the affected corneas were evaluated by histopathological examination. Finally, the clinical and histopathological results were compared among the groups. RESULTS: The CED area on days 2 and 7 was significantly less in the AV group than that in the MT group (P = 0.007 and P = 0.024, respectively) and the control group (P = 0.003 and P = 0.037, respectively). None of the cases developed hypersensitivity reactions, limbal ischemia, descemetocele, or corneal perforation during the study period. Based on histopathology, the AV group had notably less keratocyte loss than the MT group (P = 0.001) and the control group (P = 0.022). The inflammatory response after the alkali burn was higher in the AV group than that in the controls (P = 0.028). CONCLUSION: Short-term topical AV treatment was effective in healing alkali-burned corneas and hastened corneal re-epithelialization as compared to MT; however, AV gel-derived eye drops did not reduce the inflammatory response.

COL18A1 is a candidate eye iridocorneal angle-closure gene in humans.

Primary angle-closure glaucoma (PACG) is a common form of glaucoma in the Far East. Its defining feature is iridocorneal angle closure. In addition to PACG, indications of angle closure are included in the diagnostic criteria of related conditions primary angle-closure suspect (PACS) and primary angle closure (PAC). To the best of our knowledge, a causative gene for iridocorneal angle closure in humans has not been identified. This study aimed to identify the genetic cause of iridocorneal angle closure in a pedigree with at least 10 individuals diagnosed with PACS, PAC or PACG. Results of linkage analysis, segregation analysis of 44 novel variations, whole exome sequencing of 10 individuals, screenings of controls and bioinformatics predictions identified a mutation in COL18A1 that encodes collagen type XVIII as the most likely cause of angle closure in the pedigree. The role of COL18A1 in the etiology of Knobloch syndrome (KS) that is consistently accompanied by optic anomalies, available functional data on the encoded protein and the recognized role of collagens and the extracellular matrix in glaucoma pathogenesis supported the proposed role of the COL18A1 mutation in the pedigree. Subsequent identification of other COL18A1 mutations in PACS affected individuals of two unrelated families further supported that COL18A1 may affect angle closure. These PACS individuals were parents and grandparents of KS-affected children. In conclusion, a gene that affects angle closure in humans, a critical feature of PACG, has been identified. The findings also reinforce the importance of collagens in eye features and functions.

Effect of Suture Removal on Refraction and Graft Curvature After Deep Anterior Lamellar Keratoplasty in Patients With Keratoconus.

PURPOSE: To evaluate the effect of suture removal on refraction and keratometry measurements after deep anterior lamellar keratoplasty (DALK). METHODS: This retrospective study enrolled 54 keratoconus-affected eyes that underwent DALK. A combined suturing technique consisting of a 16-bite single running and 8-bite interrupted 10-0 nylon sutures was used at the time of keratoplasty. Selective interrupted suture removal was performed in a subgroup of patients to reduce postkeratoplasty astigmatism. In another subgroup, all sutures were removed at a single session. Adjustment of the running suture tension was not performed in any case. The effect of suture removal on refractive outcomes was investigated in the entire study group, and the 2 subgroups were compared. RESULTS: Mean patient age was 26.6 ± 6.7 years at the time of keratoplasty. The mean interval from surgery to complete suture removal was 17.4 ± 5.9 months. Compared with the pre-suture removal values, there was a significant increase in the magnitude of myopia (-1.12 ± 1.73 D, P = 0.001), refractive astigmatism (-0.89 ± 2.47 D, P = 0.04), mean keratometry (1.39 ± 1.64 D, P = 0.001), and keratometric astigmatism (2.61 ± 2.43 D, P < 0.001) after complete suture removal. Subgroup analysis revealed that selective removal of interrupted sutures was effective as long as remaining interrupted and running sutures were left in place. CONCLUSIONS: Complete suture removal was followed by an unpredictable and significant increase in post-DALK refraction and keratometry readings. In the subgroup that underwent early selective removal of interrupted sutures before complete suture removal, the desirable effects of this procedure significantly diminished after all remaining sutures were completely removed.

Clinical Practice Guidelines for Prevention, Diagnosis and Management of Early and Delayed-onset Ocular Injuries Due to Mustard Gas Exposure.

PURPOSE: To develop clinical practice guidelines (CPGs) for prevention, diagnosis, treatment and follow-up of ocular injuries caused by exposure to mustard gas. METHODS: The clinical questions were designed by the guideline team. Websites and databases including National Guidelines Clearinghouse, National Institute for Clinical Excellence, Cochrane, and PubMed were searched to find related CPGs and explore possible answers to the clinical questions. Since there were no relevant CPGs in the literature, related articles in Persian and English languages were extracted. Each article along with its level of evidence was summarized. Additionally, hand search was performed by looking the reference list of each article. Consequently, recommendations were developed considering the clinical benefits and side effects of each therapeutic modality. The recommendations were re-evaluated in terms of customization criteria. All recommendations along with the related evidence were scored from 1 to 9 by experts from all medical universities of Iran. The level of agreement among the experts was evaluated by analyzing the given scores. RESULTS: The agreement was achieved for all recommendations. The experts suggested a number of minor modifications which were applied to the recommendations. Finally, CPGs were developed with 98 recommendations under three major domains including prevention of injury, diagnosis and management of the acute and delayed-onset mustard gas ocular injuries. CONCLUSION: Considering the lack of CPGs for the prevention, diagnosis, and management of mustard gas-induced keratitis, these recommendations would be useful to prevent the serious ocular complications of mustard gas and standardize eye care services to the affected individuals.

Three Methods for Correction of Astigmatism during Phacoemulsification.

PURPOSE: To compare the safety and efficacy of three methods for correcting pre-existing astigmatism during phacoemulsification. METHODS: This prospective, comparative, non-randomized study was conducted from March 2010 to January 2011, and included patients with keratometric astigmatism ≥1.25 D undergoing cataract surgery. Astigmatism was corrected using the following approaches: limbal relaxing incisions (LRI) on the steep meridian, extension and suturing of the phaco incision created at the steep meridian (extended-on-axis incision, EOAI), and toric intraocular lens (tIOL) implantation. Keratometric and refractive astigmatism were evaluated 1, 8, and 24 weeks postoperatively. RESULTS: Eighty-three eyes of 72 patients (35 male and 37 female) with mean age of 62.4 ± 14.3 (range, 41-86) years were enrolled. The astigmatism was corrected by using the LRI, EOAI and tIOL implantation methods in 17, 33 and 33 eyes, respectively. Postoperative uncorrected distance visual acuity (UDVA) was significantly improved in all three groups. The difference in postoperative UDVA was not statistically significant among the study groups throughout follow-up except at week 24, when UCVA was significantly better in the tIOL group as compared to the EOAI group (P = 0.024). There is no statistically significant difference of correction index and index of success between three groups at week 24 (P = 0.085 and P = 0.085 respectively). CONCLUSION: There was no significant difference in astigmatism reduction among the three methods of astigmatism correction during phacoemulsification. Each of these methods can be used at the discretion of the surgeon.

Deep Anterior Lamellar Keratoplasty in Keratoconic Patients with versus without Vernal Keratoconjunctivitis.

PURPOSE: To compare the clinical outcomes of deep anterior lamellar keratoplasty (DALK) for keratoconus in patients with vernal keratoconjunctivitis (VKC) versus those without VKC. METHODS: In this retrospective comparative study, records of 262 eyes with keratoconus (Group 1) and 28 keratoconic eyes with VKC (Group 2) that had undergone DALK were compiled. Reviewed parameters included length of follow-up, best-corrected visual acuity (BCVA), refractive error, complications and cumulative graft survival. RESULTS: Mean duration of follow-up was 38.6 ± 20.2 and 34.4 ± 20.9 months in groups 1 and 2, respectively (P = 0.21). Mean post-operative BCVA was 0.19 ± 0.11 and 0.20 ± 0.15 logMAR, in groups 1 and 2 (P = 0.79). BCVA≥20/40 was achieved in 91.6 and 88.5% of eyes in groups 1 and 2, respectively (P = 0.48). Epithelial problems were encountered in 31.3 and 42.9% of operated eyes, respectively (P = 0.16). Vascularization of suture tracts and stitch abscesses were encountered more frequently in the eyes with VKC (P = 0.01 and <0.001, respectively). At the 33-month follow-up examination, rejection-free graft survival rates were 56.0% in group 1 and 33.3% in group 2, with mean durations of 41.0 and 32.1 months, respectively (P = 0.15). Graft survival rates were 98.1% in group 1 and 95.0% in group 2, with mean durations of 88.6 and 88.4 months, respectively (P = 0.74). CONCLUSION: Clinical outcomes of DALK in keratoconic eyes with VKC were comparable to those in eyes with keratoconus alone. However, complications such as suture tract vascularization and stitch abscesses were more common when VKC coexisted, necessitating closer monitoring.

Prevalence and Risk Factors for Trachoma in Rural Areas of Sistan-va-Baluchestan Province, Iran: A Population-Based Study.

PURPOSE: To determine the prevalence of trachoma and risk factors associated with the disease in rural areas of the Sistan-va-Baluchestan province in Iran from 2012-2013. Population-based prevalence data for trachoma is lacking in this region. METHODS: In this population-based cross-sectional study, 80 clusters were selected using a systematic and probability proportional to size method. All participants underwent clinical eye examinations according to the World Health Organization simplified trachoma grading system. The prevalence of follicular trachoma (TF) in children aged 1-9 years and the prevalence of trachomatous trichiasis (TT) in women aged over 15 years were the most important clinical indicators of trachoma. RESULTS: The study surveyed 8187 individuals and analyzed 7912 participants (96.6%) including 3737 children aged 1-9 years and 4175 females >15 years. The prevalence of TF and TT in the relevant indicator groups were 0.59% (95% confidence interval, CI, 0.36-0.89%) and 0.02% (95% CI 0.00-0.13%), respectively. CONCLUSION: Previously, trachoma prevalence data for this region were lacking. This study confirms that the Sistan-va-Baluchestan region is not endemic for trachoma. This has important implications for national trachoma elimination activities.

Sensitivity and specificity of posterior and anterior corneal elevation measured by orbscan in diagnosis of clinical and subclinical keratoconus.

PURPOSE: To determine the sensitivity and specificity of anterior and posterior corneal elevation parameters as determined by Orbscan II (Bausch and Lomb, Rochester, NY, USA) in discriminating between (sub) clinical keratoconus (KCN) and normal corneas. METHODS: This prospective case-control study included 28 eyes with subclinical KCN, 65 with clinical KCN and 141 normal corneas. Anterior and posterior corneal elevation was measured and compared in the central 5-mm corneal zone using Orbscan II. RESULTS: Receiver operating curves (ROC) curve analyses for posterior corneal elevation showed predictive accuracy in both KCN and subclinical KCN with an area under the curve (AUC) of 0.97 and 0.69, respectively while optimal cutoff points were 51 µm for KCN and 35 µm for subclinical KCN. These values were associated with sensitivity and specificity of 89.23% and 98.58%, respectively, for KCN; and 50.00% and 88.65% for subclinical KCN. ROC curve analyses for anterior corneal elevation showed predictive accuracy in both KCN and subclinical KCN with AUC of 0.97 and 0.69, respectively while optimal cutoff points were 19 µm for KCN and 16 µm for subclinical KCN. These values were associated with sensitivity and specificity of 93.85% and 97.16%, respectively, for KCN; and 60.71% and 87.94% for subclinical KCN. CONCLUSION: Anterior and posterior corneal elevation data obtained by Orbscan II can well discriminate between KCN and normal corneas, however the reliability of their indices is lower in differentiating subclinical KCN from normal cases.

Customized Clinical Practice Guidelines for Management of Adult Cataract in Iran.

PURPOSE: To customize clinical practice guidelines (CPGs) for cataract management in the Iranian population. METHODS: First, four CPGs (American Academy of Ophthalmology 2006 and 2011, Royal College of Ophthalmologists 2010, and Canadian Ophthalmological Society 2008) were selected from a number of available CPGs in the literature for cataract management. All recommendations of these guidelines, together with their references, were studied. Each recommendation was summarized in 4 tables. The first table showed the recommendation itself in clinical question components format along with its level of evidence. The second table contained structured abstracts of supporting articles related to the clinical question with their levels of evidence. The third table included the customized recommendation of the internal group respecting its clinical advantage, cost, and complications. In the fourth table, the internal group their recommendations from 1 to 9 based on the customizing capability of the recommendation (applicability, acceptability, external validity). Finally, customized recommendations were sent one month prior to a consensus session to faculty members of all universities across the country asking for their comments on recommendations. RESULTS: The agreed recommendations were accepted as conclusive while those with no agreement were discussed at the consensus session. Finally, all customized recommendations were codified as 80 recommendations along with their sources and levels of evidence for the Iranian population. CONCLUSION: Customization of CPGs for management of adult cataract for the Iranian population seems to be useful for standardization of referral, diagnosis and treatment of patients.

Modified big-bubble deep anterior lamellar keratoplasty using peripheral air injection.

PURPOSE: To introduce a modification to big-bubble deep anterior lamellar keratoplasty (DALK) which can decrease the risk of Descemet membrane (DM) perforation during air injection. METHOD: In Anwar's big-bubble technique, a 27-guage needle is inserted from the trephination site and advanced into the corneal stroma up to the centre. The technique we introduce modifies the original technique in the following fashion. After trephination to approximately 80% of corneal thickness, a 27-guage needle is inserted into the stroma peripherally from the trephination site towards the limbus. Air is injected gently into the deep stroma until a big bubble is formed. This technique was performed in 16 consecutive keratoconic eyes undergoing DALK. Additionally, peripheral air injection was carried out in 27 eye-bank corneas using a peripheral approach. RESULTS: In all (100%) eye-bank and 13 (81.3%) live corneas, a successful big bubble was easily achieved following peripheral air injection. In these 13 live corneas, all bubbles were formed at the central (n=10) or paracentral (n=3) cornea and extended centrifugally (type 1 bubble). In one of these corneas, an additional three bubbles were noted in the periphery between the DM and the pre-Descemet posterior stromal layer (Dua's layer, type 2) after a type 1 bubble was formed. In two live corneas in which peripheral air injection failed, a big bubble was successfully formed after air was injected inside the trephination site. CONCLUSIONS: Air injection peripheral to the trephination site is a reproducible modification to the standard technique which can decrease the risk of DM perforation during air injection.

Central and peripheral corneal thickness measurement in normal and keratoconic eyes using three corneal pachymeters.

PURPOSE: To assess the agreement among ultrasonic pachymetry, the Galilei dual Scheimpflug analyzer, and Orbscan II for central and peripheral (Galilei vs. Orbscan) corneal thickness (CCT and PCT) measurement in normal and keratoconic eyes. METHODS: In this prospective study, CCT and PCT were measured in 88 eyes of 88 refractive surgery candidates and 128 eyes of 69 keratoconic patients with ultrasonic pachymetry, the Galilei, and Orbscan II. The readings by the three instruments were compared using one-way analysis of normal variance. Agreement among the three devices was assessed using Pearson and intraclass correlation coefficients, and Bland-Altman plots. The same analyses were employed to evaluate agreement between Galilei and Orbscan II for PCT measurement. RESULTS: In the normal group, mean CCT was 551.0±39.4, 566.9±33.5, and 565.5±40.9 µm measured by ultrasonic pachymetry, the Galilei, and Orbscan II, respectively (P<0.001). The corresponding figures in the keratoconus group were 492.0±61.7, 502.0±42.1, and 470.6±56.9 µm, respectively (P<0.001). Mean PCT was 612.5±35.3 and 640.9±38.0 µm in the normal group (P<0.001) and 567.6±35.2 and 595.1±41.4 µm in the keratoconus group (P<0.001) by the Galilei and Orbscan II, respectively. CCT and PCT measurements obtained by different devices were significantly correlated in both groups. CONCLUSION: To measure CCT, the Galilei and Orbscan II can be used interchangeably in normal eyes, but not in keratoconic eyes. For PCT, there is a systematic error between measurements obtained by the Galilei and Orbscan II. However, it is possible to change optical pachymeter readings into those obtained by ultrasonic pachymetry using a constant.

Evaluation of corneal elevation in eyes with subclinical keratoconus and keratoconus using Galilei double Scheimpflug analyzer.

PURPOSE: To measure corneal elevations in eyes with subclinical keratoconus and those with keratoconus using the Galilei Scheimpflug analyzer and to determine the optimal corneal elevation cutoff points to maximize sensitivity and specificity in discriminating keratoconus and subclinical keratoconus from normal corneas. 
 METHODS: A total of 136 normal eyes, 23 eyes with subclinical keratoconus, and 51 eyes with keratoconus were enrolled. Maximum anterior and posterior corneal elevation was measured in the central 3-, 5-, and 7-mm zones using the Galilei double Scheimpflug camera. Receiver operating characteristic curves were used to compare the sensitivity and specificity of the measured parameters and to identify optimal cutoff points for discriminating keratoconus and subclinical keratoconus from normal corneas. 
 RESULTS: Mean anterior and posterior corneal elevations in all zones were statistically higher in keratoconus and subclinical keratoconus versus normal corneas. The posterior elevation measurement in the 3-mm zone had the strongest power to distinguish keratoconus from normal. The corresponding figure for the 7-mm zone, however, had the strongest power to distinguish eyes with subclinical keratoconus (area under the curve, 0.98 and 0.92, respectively). Optimal cutoff point for posterior elevation in the 3-mm zone was 18.5 µm for keratoconus (sensitivity, 92%; specificity, 95%). The corresponding figure in the 7-mm zone was 50.5 µm for subclinical keratoconus (sensitivity, 79.9%; specificity, 94.0%). 
 CONCLUSIONS: Anterior and posterior elevations measured by the Galilei analyzer in the 3-mm zone can effectively discriminate keratoconus from normal corneas. These measurements in the 7-mm zone can be considered to distinguish subclinical keratoconus.