Corneal biomechanical changes after Descemet stripping automated endothelial keratoplasty, penetrating keratoplasty, and phacoemulsification.

PURPOSE: To evaluate corneal biomechanical changes after Descemet stripping automated endothelial keratoplasty (DSAEK), penetrating keratoplasty (PK), and phacoemulsification (PE). METHODS: This prospective study included 138 eyes which underwent PK (26 eyes), DSAEK (26 eyes), PE (57 eyes), and 29 normal eyes. Intraocular pressure (IOP) was measured by Goldmann applanation tonometer (GAT), and central corneal thickness (CCT) and axial length by ultrasound. The ocular response analyzer was used to measure corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann-related IOP (IOPg), and cornea-compensated IOP (IOPcc) preoperatively and 1, 3, and 6 months postoperatively. RESULTS: At baseline, PK group had the lowest CH and CRF. There was a significant increase in CH and CRF to normal values in PK (P = 0.015 and 0.006) and PE (P = 0.005 and 0.0001) groups over the study period. At 6 months, CH and CRF increased and reached normal values in the PK group; increased to a lower level than normal in the DSAEK group; and, after an initial reduction, increased to normal values in the PE group. At 6 months, DSAEK group had the lowest CH and CRF. There was a significant positive correlation between CRF and GAT (r = 0.281, P = 0.009), IOPg and GAT (r = 0.335, P = 0.001), and IOPcc and GAT (r = 0.282, P = 0.001). CH was negatively correlated with age (r = - 0.189, P = 0.04). CONCLUSION: Corneal biomechanical factors increase after DSAEK and PK. At post-operative month six, they reach normal values in PK group, but are lower than normal in DSAEK group.

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.

Age-related variations in corneal biomechanical properties.

PURPOSE: To determine age-related changes in corneal viscoelastic properties in healthy individuals. METHODS: This observational cross-sectional study was performed at the Department of Ophthalmology, Imam Khomeini Hospital, Ahvaz, Iran and included 302 healthy individuals in 6 age decades (range: 10-69 years). After complete ocular examination, corneal viscoelastic properties were measured by ocular response analyzer and central corneal thickness (CCT) by an ultrasonic pachymeter. Our main outcome measures were corneal viscoelastic properties in different age groups. RESULTS: Corneal hysteresis (CH) and corneal resistance factor (CRF) showed a significant negative correlation with age (P < 0.001 for both, r = -0.353 and r = -0.246, respectively). Female gender had significantly higher CH (P = 0.017) and CRF (P = 0.019). CH and CRF were significantly correlated (P < 0.001, r = 0.821). CCT showed a biphasic pattern with significantly higher thicknesses before 20 and after 50 years of age. CH and CRF were significantly correlated with CCT (P < 0.001 for both, r = 0.21 and r = 0.26, respectively) and intraocular pressure (IOP) (P < 0.001 for both, r = -0.474 and r = 0.598, respectively). Corneal-compensated IOP (IOPcc) was significantly higher after age 40 compared to age group <20 (p < 0.045). Goldmann-correlated IOP (IOPg) was significantly correlated with CCT (P = 0.001, r = 0.193), while IOPcc showed no correlation with CCT (P = 0.265, r = 0.062). CH was significantly higher in hyperopic eyes compared to emmetropic eyes (P = 0.009) and myopic eye (P < 0.001). CONCLUSIONS: In this study, there was a decrease in CH and CRF with an increase in age. Hyperopia and female gender are associated with higher CH and CRF. CCT is higher toward the extremes of life and is significantly correlated with CH and CRF.

Oxygen therapy for corneal edema after cataract surgery.

PURPOSE: To evaluate the effects of oxygen therapy on corneal edema after cataract surgery. SETTING: Imam Khomeini Hospital, Ahvaz, Iran. DESIGN: Randomized controlled trial. METHODS: Patients with severe corneal edema were randomized into 3 groups. Group 1 (control) received conventional therapy including topical sodium chloride, timolol, and betamethasone. Group 2 received the same therapy in addition to systemic normobaric oxygen at a flow rate of 10 L/min for 1 hour twice daily for 3 weeks. Group 3 received conventional therapy and transcorneal oxygen at a flow rate of 5 L/min for 1 hour twice daily for 3 weeks. Preoperative pachymetry and specular microscopy were performed. Pachymetry was performed 1, 3, 5, 7, 10, and 14 days postoperatively. At 1, 3 and 12 months, pachymetry and specular microscopy were performed. RESULTS: The study enrolled 45 patients. Preoperatively, there was no significant difference between the groups. Pachymetry was more than 1000 µm 1 day postoperatively in all patients. The preoperative pachymetry was restored in 14 days in Group 3 only. After 1 year, the endothelial cell count (ECC) was 1603 cells/mm(2), 1693 cells/mm(2), and 1911 cells/mm(2) with a loss of 37%, 32%, and 25% in Group 1, Group 2, and Group 3, respectively (P = .034, Groups 1 and 3). Group 3 had a higher ECC than the control group at 3 months (P = .037) and 1 year (P = .025). One patient in Group 1 and 1 patient in Group 2 developed bullous keratopathy. CONCLUSION: Transcorneal oxygen decreased corneal edema more rapidly than conventional and systemic oxygen therapies and preserved more endothelial cells than conventional therapy. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.

Corneal Collagen Cross-linking for Treatment of Non-healing Corneal Ulcers.

PURPOSE: To evaluate the efficacy of corneal collagen cross-linking (CXL) for treatment of corneal ulcers not responding to antimicrobial therapy. METHODS: Eight patients with corneal ulcers associated with corneal melting, not responding to conventional antibiotic therapy, were treated with CXL. The procedure was performed according to the standardized protocol for keratoconus. Preoperative medications were continued after CXL in all cases. Microbiological exams revealed Pseudomonas aeruginosa in 3 cases. Follow up continued from 1 to 10 months. RESULTS: In 6 of 8 eyes, progression of corneal melting was halted and complete epithelialization occurred. In one eye emergency keratoplasty was needed due to corneal perforation. A conjunctival flap was performed to treat severe localized corneal thinning in one of the patients a few days after CXL. Significant clinical improvement occurred in all cases of Pseudomonas aeruginosa keratitis. CONCLUSION: CXL can be considered as a promising new treatment in the management of refractory non-healing corneal ulcers, including Pseudomonas aeruginosa keratitis.

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 Descemet's Stripping Automated Endothelial Keratoplasty for Congenital Hereditary Endothelial Dystrophy.

A 19-year-old male with congenital hereditary endothelial dystrophy (CHED) presented with severe bilateral corneal clouding precluding any view of the intraocular structures. He underwent modified Descemet's stripping automated endothelial keratoplasty (DSAEK) technique including a suture pull-through technique to prevent lens damage. Surgery resulted in progressive clearing of the cornea and decreased corneal thickness. Visual acuity increased from hand motions preoperatively to counting fingers at 4 m after 4 months. DSAEK can be successfully performed in phakic eyes with CHED as an alternative to penetrating keratoplasty. It has the advantage of less wound problems and better preservation of globe integrity especially in children.

Normobaric oxygen therapy for scleral ischemia or melt.

PURPOSE: To investigate the efficacy of normobaric oxygen (NBO) therapy for treatment of scleral ischemia or melt. METHODS: This prospective interventional case series includes 9 eyes of 8 patients with scleral ischemia or melt of diverse etiologies. Following the failure of conventional medical and/or surgical therapy to improve ischemia or upon clinical deterioration, NBO was initiated. All patients received 100% NBO at flow rate of 10 liters/minute by face mask for 1 hour, twice daily until complete vascularization of ischemic areas. Main outcome measures were improvement of scleral ischemia and healing of conjunctival epithelial defects. RESULTS: NBO therapy led to epithelialization and vascularization of the ischemic sclera in all eyes; the repair process began 3-4 days after NBO had been initiated and was completed in 18.1±4.7 (range, 10-25) days. All patients remained stable over a 9-month follow-up period. CONCLUSION: NBO therapy seems effective for treatment of scleral ischemia or melt, and hence can be considered as a non-invasive alternative to surgical intervention in these conditions.