Journal of Ophthalmic and Vision Research
Year:2009 | Volume:4 | Issue:1|Papers Count:11

Penetrating keratoplasty (PKP) has a long track record of high success rates compared to other tissue and organ transplantations. Despite the immunologic privilege of the cornea, the issue of immunological rejection cannot be overlooked and endothelial rejection is observed in up to 20% of eyes undergoing PKP.1 Repeat keratoplasties after rejection are increasingly more prone to rejection and the potential for a clear cornea becomes progressively lower with subsequent PKPs. Prospective long-term graft survival studies have also revealed disappointing results with PKP, and it is now recognized that graft survival rates and endothelial cell counts continue to decrease for many years after PKP.

Purpose: To evaluate the visual outcomes and complications of deep anterior lamellar keratoplasty (DALK) using the big-bubble technique in patients with keratoconus. Methods: In this case series, 104 eyes of 99 patients with moderate to advanced keratoconus underwent DALK. All subjects were contact lens intolerant or had unacceptable spectacle-corrected visual acuity. DALK was performed using the big-bubble technique. Full thickness donor corneas devoid of Descemet’s membrane (DM) were sutured to the recipient bed. Best spectacle-corrected visual acuity (BSCVA), refractive status, and intra- and postoperative complications were evaluated.Results: Patients were male in 62.5%. Mean age of patients was 26.2±7.79 (range 15-46) years at the time of DALK and were followed for 23.07±8.1 (range 9-42) months. Mean BSCVA increased from 1.23±0.4 logMAR to 0.26±0.2 logMAR at final follow-up (P<0.001). Postoperative mean spherical equivalent refractive error and refractive and keratometric astigmatism were -3.41±3.1 D, 3.07±2.4 D, and 3.64±2.2 D, respectively. Bared DM was achieved in 86 (82.7%) eyes. Main complications encountered included filamentary keratitis (19.2%), non-endothelial graft rejection (14.4%), and suture abscess (10.6%).Conclusions: DALK using the big-bubble technique appears to be a safe and effective procedure in patients with keratoconus.

Purpose: To report the outcomes of penetrating keratoplasty (PKP) in patients with macular corneal dystrophy (MCD).Methods: This retrospective case series includes consecutive patients with MCD who underwent PKP from 1986 to 2006 with at least 6 months’ follow-up. Main outcome measures included best spectacle-corrected visual acuity (BSCVA), postoperative astigmatism and graft survival.Results: Sixty-two eyes of 39 patients with mean age of 34.0±10.5 (range 13-58) years at the time of keratoplasty were included for analysis. After a mean follow-up period of 52.0±47.3 (range 6-190) months, BSCVA improved from 1.4±0.4 logMAR (4/100) preoperatively to 0.2±0.3 logMAR (20/32) at final follow-up (P<0.001). Mean postoperative BSCVA was 0.15±0.40 logMAR in patients (36 eyes) aged less than 35 years at the time of surgery as compared to 0.26±0.25 logMAR in subjects (26 eyes) older than 35 years (P=0.005). Final astigmatism was comparable with different suturing techniques including separate, continuous, and combined sutures (P=0.9). All grafts were clear at final follow-up except a single case of MCD with visually insignificant recurrence. Episodes of immunologic graft rejection occurred in 12 eyes (19.4%) but none led to graft failure.Conclusion: PKP for MCD entails favorable outcomes in terms of graft survival and visual improvement. Final visual acuity seems to be better when transplantation is performed before the age of 35 years.

Purpose: To compare the efficacy of topical cefazolin-gentamicin versus vancomycinceftazidime for treatment of bacterial corneal ulcers.Methods: This randomized double-masked clinical trial was performed on consecutive patients with bacterial corneal ulcers referred to Feiz Hospital, Isfahan, Iran from 2004 to 2005. Patients were randomly assigned to cefazolin-gentamicin or vancomycin-ceftazidime eye drops in a masked fashion. Outcome measures included time for resolution of stromal infiltration, re-epithelization of the epithelial defect, and clearance of anterior chamber inflammation as well as culture results and complications.Results: The study included 89 eyes of 89 patients with bacterial corneal ulcers consisting of 57 (64%) male and 32 (36%) female subjects. Specimens were culturenegative in 46% of cases. Forty-one eyes received cefazolin-gentamicin and 48 eyes were treated with vancomycin-ceftazidime. Time for resolution of stromal infiltration was 17.7±4.3 days versus 13.8±3.6 days (P=0.04), time to complete re-epithelization was  13.2±3.1 days versus 9.6±2.7 days (P=0.01) and time for clearing of the anterior chamber was 11.6±2.9 days versus 8.1±2.3 days (P=0.04) in the cefazolin-gentamicin and vancomycin-ceftazidime groups, respectively. The most common complaint related to the medications was ocular burning in 73.1% of patients treated with cefazolingentamicin and 62.9% of cases receiving vancomycin-ceftazidime (P=0.007).Conclusion: Vancomycin-ceftazidime eye drops seem to be more effective than cefazolin-gentamicin eye drops for the treatment of bacterial corneal ulcers and are probably better tolerated locally.

Purpose: To report the incidence, severity and risk factors of retinopathy of prematurity (ROP) in premature infants with late ROP examination in Farabi Eye Hospital.Methods: In a retrospective study from January 2001 to July 2007, hospital records of premature infants who were examined later than 9 weeks after birth were reviewed to determine the incidence, severity and possible risk factors of ROP including gender, singleton or multiple gestations, gestational age (GA), birth weight (BW), oxygen therapy, blood transfusion, phototherapy, respiratory distress syndrome (RDS), mechanical ventilation, intraventricular hemorrhage and sepsis as well as age at initial examination. Results: Out of a total of 797 infants referred for ROP screening during the study period, 216 (27.1%) had late examinations at a mean age of 141.7±150.4 (range 64-1,460) days. Of these, 87 (40.3%) had different stages of ROP, 65 (30.1%) had stage 4 or 5 disease including 34 (16.2%) infants with stage 5 ROP in both eyes which was untreatable. Lower GA (P<0.001), RDS (P=0.041) and blood transfusion (P=0.009) were associated with the development of ROP.Conclusion: The overall prevalence of ROP and the incidence of severe ROP in particular, were unacceptably high in premature infants with late screening. These findings necessitate interventions to optimize timely referral for screening of premature infants.

Purpose: To determine the prevalence and causes of blindness and low vision in Khuzestan province, Iran in 2006.Methods: This population-based cross-sectional study included residents of Khuzestan province during the year 2006. The study was designed according to World Health Organization (WHO) recommendations. Multi-stage proportionate clustered random sampling was employed. Sample size was calculated according to the latest national census and estimated rates of blindness. Initially data accumulation including general information and optometrists' findings was performed at local health centers, followed by referral of subjects with best-corrected visual acuity less than 20/60 for a comprehensive ophthalmologic examination. Categorization of blindness and low vision was based on WHO criteria and causes of visual impairment were classified according to the International Classification of Diseases version 10.Results: Overall, 6,960 subjects with mean age of 24.7±18.3 years (range 3 months to 87 years) participated in the study (74.5% response rate). The prevalence of bilateral blindness and low vision in subjects older than 5 years was 1.3% and 2.6%, respectively; a significant positive trend was observed with increasing age (P<0.001) but no significant correlation was noted with sex and domicile. The leading causes of visual impairment included cataracts (39.0%), refractive errors (37.9%) and amblyopia (23.6%). A minority of cases were due to surgical complications (1.9%) and trauma (1.3%). Conclusion: Blindness and low vision in Khuzestan province occurred at an average rateas compared to similar countries. It is estimated that there are 28,537 and 105,995 cases of bilateral blindness and low vision respectively in this province.

Purpose: To evaluate early and late histopathologic changes following posterior sub-Tenon injection of atracurium in the rabbit eye.Methods: This study was performed on 39 healthy white New Zealand rabbits which received sub-Tenon injection of 0.05-0.08 mg/kg atracurium diluted in 0.5 ml normal saline (N/S) in the left and 0.5 ml N/S in the right eyes. Bilateral enuclation was performed one hour after the injection to evaluate early changes in 19 rabbits and one week later to determine late changes in the remaining 20 animals. After enucleation, the rabbits were euthanized. Enucleated eyes were sent in 10% formalin solution for histopathologic examination. After processing, the specimens were evaluated by light microscopy following staining with hematoxylin and eosin, and trichrome.Results: Congestion was more common in the control group 1 hour after injection. Liquifaction necrosis was seen in both groups but was significantly increased one week after the injection in the atracurium group.Conclusion: Congestion is a transient complication related to injection which disappears after one week, but necrosis seems to be an important late complication of atracurium injection.

The ocular surface consists of two distinct types of epithelial cells; conjunctival and corneal. Although anatomically continuous, these epithelia comprise two distinct cell populations. Corneal stem cells are located at the limbus. The microenvironment of the limbus is important in maintaining “stemness” of the stem cells and also acts as a barrier to conjunctival epithelial cells preventing them from migration onto the corneal surface. Damage to the limbus results in varying degrees of limbal stem cell deficiency with characteristic clinical features including conjunctivalization of the cornea. Regenerative management of corneal conjunctivalization utilizing stem cells comprises of two approaches; limbal auto- or allografts by using existing stem cells and induction and regeneration of ocular tissues from embryonic stem cells. Herein, we review stem cells and limbal stem cells in particular, types of epithelial cells in the cornea, markers of corneal epithelial cells in different stages, as well as the current approach to corneal epithelial regeneration.

Purpose: To report a case of posterior ischemic optic neuropathy (PION) following herpes zoster ophthalmicus (HZO).Case Report: A 58-year-old woman with history of recent HZO in her right eye presented with acute painless loss of vision in the same eye to no light perception. Examination revealed a positive relative afferent pupillary defect and a normal appearing optic disc. Inflammatory and infiltrative lesions of the optic nerve were ruled out by laboratory and imaging studies. The patient received systemic acyclovir and prednisolone. Three months later, visual acuity improved to counting fingers, but the optic disc became pale and atrophic leading to a presumptive diagnosis of PION.Considering the positive PCR test for varicella zoster virus and the short time interval between the two presentations, HZO was considered as the most probable cause of the optic neuropathy.Conclusion: Herpes zoster ophthalmicus can be associated with PION.

A 59-year-old woman with history of noninsulin dependent diabetes mellitus and systemic hypertension presented with decreased vision in her left eye since 2 months ago. Bestcorrected visual acuity (BCVA) was 20/20 and 20/400 in the right and left eyes respectively.Relative afferent pupillary defect was negative. Anterior segment examination was unremarkable except for mild posterior subcapsular cataracts bilaterally.

The principle of gene therapy involves the introduction of exogenous DNA into the host tissue followed by its expression by host transcription-translational system leading to production of RNA, DNA, peptides or proteins. Advances in molecular biology and genetics have revealed the molecular basis of various diseases and developments in gene transfer technology have contributed to recent progress in the field of gene therapy.