Journal of Ophthalmic and Vision Research
Year:2009 | Volume:4 | Issue:3|Papers Count:13

Retinal pigment epithelial (RPE) stem cells offer a theoretical treatment strategy for a wide variety of retinal disorders including age-related macular degeneration (AMD) and retinal dystrophies. There are, however, a number of hurdles that will have to be overcome before a consistently reliable and successful therapy can be offered to patients. These include expansion of sufficient numbers of suitably differentiated cells for transplantation, technical issues around insertion of the cells and removal of damaged tissue (such as abnormal Bruch’s membrane in AMD), immunological rejection of transplanted cells, and control of post-transplant cell differentiation.1-3 Thus, in the case of RPE cell replacement, it may ultimately be proven that transplantation of an expanded number of differentiated cells on a porous substrate can deal with issues such as control of differentiation, prevention of proliferative vitreoretinopathy and replacement of damaged Bruch’s membrane.

Purpose: To establish human retinal pigment epithelial (RPE) cell culture as a source for cell replacement therapy in ocular diseases. Methods: Human cadaver globes were used to isolate RPE cells. Each globe was cut into several pieces of a few millimeters in size. After removing the sclera and choroid, remaining tissues were washed in phosphate buffer saline and RPE cells were isolated using dispase enzyme solution and cultured in Dulbecco’s Modified Eagle’s Medium: Nutrient Mixture F-12 supplemented with 10% fetal calf serum. Results: Primary cultures of RPE cells were established and spheroid colonies related to progenitor/stem cells developed in a number of cultures. The colonies included purely pigmented or mixed pigmented and non-pigmented cells. After multiple cellular pass-ages, several types of photoreceptors and neural-like cells were detected morpho-logically. Conclusion: Cellular plasticity in RPE cell cultures revealed promising results in terms of generation of stem/progenitor cells from human RPE cells. Whether the spheroids and neural-like retinal cells were directly derived from retinal stem cells or offspring of trans-differentiating or de-differentiating RPE cells remains to be answered.

Purpose: To report the efficacy, safety, predictability and complications of photorefractive keratectomy (PRK) with intraoperative application of mitomycin-C (MMC).Methods: This historical cohort study was performed on 1,250 eyes of 625 patients who underwent PRK using the Technolas 217 excimer laser machine by a single surgeon with intraoperative use of MMC 0.02% up to 2 minutes, depending on depth of ablation. A complete ophthalmologic examination was performed which included refraction, uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA) and slitlamp biomicroscopy. Outcomes were analyzed after one year of follow-up. Results: The mean preoperative spherical equivalent refractive error was -4.85±2.27 (range, -2.50 to -13.5) diopters (D). Mean depth of ablation was 89±22 microns and mean time to reepithelialization was 4.5±1.7 days. At final follow-up, UCVA of 20/20 and 20/40 or more was achieved in 92.1% and 99.2% of eyes, respectively. One year postoperatively, 69.4% and 91% of eyes were within ±0.50 D and ±1.00 D of emmetropia. Overall, 62 eyes (4.9%) developed one or two lines of decrease in BCVA, and 50 eyes (4%) developed corneal haze which was grade 1 or 2 in most cases; grade 3 and 4 corneal haze was found in 4 and 2 eyes, respectively. No other adverse event was noted during the study period.Conclusion: PRK with intraoperative application of MMC provides excellent visual outcomes with acceptable safety and predictability, and entails minimal side effects.

Purpose: To determine the prevalence of calibration errors in Goldmann applanation tonometers at Farabi Eye Hospital.Methods: This cross-sectional study was performed on all tonometers in use at Farabi Eye Hospital. All Haag-Streit Goldmann applanation tonometers were checked according to the manufacturer’s method by two independent observers and by a third observer in case of mismatched results. Calibration errors were classified into 6 categories of ±0.5, ±1, ±1.5, ±2, ±2.5 and more than ±2.5 mmHg. Results: Overall, 43 Goldmann tonometers were evaluated. There were 3 (7%), 10 (24.3%), 16 (38.3%), 24 (56.9%), 31 (72.1%) and 12 (27.9%) tonometers within calibration errors of ±0.5, ±1, ±1.5, ±2, ±2.5 and more than ±2.5 mmHg respectively.Conclusion: Goldmann tonometers were not within the manufacturer's recommended range (±0.5 mmHg) in 93%, and not within the acceptable range of ±2.5 mmHg in 28% of checked devices. Further study is needed to demonstrate the correlation between calibration errors and clinical errors.

Purpose: To describe the clinical features and surgical outcomes of rhegmatogenous retinal detachment (RRD) following myopic laser in situ keratomileusis (LASIK). Methods: In a retrospective, non-comparative case series, 46 eyes that had undergone vitreoretinal surgery for management of RRD following myopic LASIK were identified. Data was reviewed with emphasis on characteristics of the RRD, employed surgical techniques, and anatomic and visual outcomes.Results: Mean pre-LASIK myopia was -9.7±3.9 (range -4.00 to -18.00) diopters (D). Mean interval between LASIK and development of RRD was 11.6±11.2 months. Posterior vitreous detachment was present in 44 eyes (95.6%). The retinal breaks included flap tears in 36 (78.3%) eyes, giant tears in 8 (17.4%) eyes and atrophic holes in 2 (4.3%) eyes. In eyes with flap tears, the breaks were multiple, large or posterior to the equator in 24 (66.7%) eyes. Retinal breaks were related to lattice degeneration in 20 (43.5%) eyes of which, three had history of prophylactic barrier laser photocoagulation. Scleral buckling was performed as the initial procedure in 32 (69.6%) eyes and primary vitrectomy was undertaken in 14 (30.4%) eyes. The initial surgical procedure failed in 14 (30.4%) eyes due to proliferative vitreoretinopathy (PVR). Retinal reattachment was finally achieved in 43 (93.4%) eyes. Postoperative visual acuity ³20/40 and ³20/200 was achieved in 16 (34.8%) and 25 (54.3%) eyes, respectively.Conclusion: Post-LASIK retinal detachment has a complex nature in eyes with moderate to high myopia. The retinal detachment is complex in terms of size, number and location of retinal breaks, is associated with a high rate of PVR and entails unfavorable visual outcomes. 

Purpose: To evaluate the association between fixation preference (FP) and amblyopia in strabismic patients. Methods: This study includes 50 patients with horizontal, vertical or mixed strabismus of at least 10 prism diopters. Best-corrected monocular visual acuity (VA) was measured using Snellen E-chart and the presence of amblyopia was determined accordingly; FP was evaluated and graded from 0 to 3.Results: Of 50 patients, including 27 female and 23 male subjects, 29 (58%) patients had FP but 18 (36%) subjects were truly amblyopic. Overall, the sensitivity and specificity of FP for detection of amblyopia was 88.9% and 59.4% respectively. The positive predictive value (PPV) and negative predictive value (NPV) were 55.2% and 90.5% respectively. Sensitivity, PPV and NPV were significantly higher in esotropic as compared to exotropic patients. Strong monocular FP was correlated with more than 3 lines of interocular difference (IOD) in visual acuity (P=0.001). Conclusion: Although FP is not an ideal method for diagnosis of strabismic amblyopia, it has high sensitivity, PPV and NPV in esotropic patients and in subjects with more than 3 lines of IOD in VA.

Purpose: To evaluate quality of life (QOL) before and after corticosteroid therapy for thyroid eye disease (TED) and to determine the impact of the disease on QOL.Methods: A modified TED-QOL questionnaire was completed by consecutive patients before and at least 6 months after steroid therapy. All patients were clinically and biochemically euthyroid during the course of the study. QOL was assessed in subscales of visual function, psychosocial, and educational/counseling; TED was classified by severity score (NOSPECS) and Mourits’ clinical activity score.Results: Overall, 61 patients including 18 (29.5%) male and 43 (70.5%) female subjects with mean age of 37.3±13.7 (range, 18-33) years were enrolled. Mean duration of thyroid dysfunction and TED were 40.1±44.8 and 26.5±38.2 months, respectively. Mean disease severity and activity significantly decreased, and visual and psychosocial function scores significantly improved following corticosteroid therapy for TED. Psychosocial score was significantly worse than visual function score before but not after steroid treatment. Linear regression analysis and Spearman correlation test showed no significant correlation between duration of thyroid dysfunction, duration of TED, disease severity and activity on one hand, and QOL scores on the other hand, before or after treatment.Conclusion: TED seems to adversely affect psychosocial activity more than visual function. Corticosteroid therapy significantly improves QOL. No significant correlation seems to exist between QOL scores and the severity or activity of TED.

Systemic chemotherapy has become the cornerstone of therapy for retinoblastoma. The advent of novel chemotherapeutic and antiangiogenesis agents together with new routes of drug administration including periocular, intravitreal and intra-ophthalmic artery injection will hopefully revolutionize the management of this sight-threatening and potentially fatal infantile ocular neoplasm.

Purpose: To report an unusual presentation of pellucid marginal degeneration (PMD).Case Report: A 57-year-old man with history of corneal ectasia experienced acute hydrops and spontaneous corneal perforation in his right eye. Examination revealed PMD in both eyes. After initial treatment with cyanoacrylate adhesive and a bandage contact lens, therapeutic penetrating keratoplasty was undertaken in the right eye. Due to severity of the condition, the fellow eye was also scheduled for penetrating keratoplasty. Conclusion: Spontaneous corneal hydrops and perforation may occur in patients with corneal ectasia due to PMD.

A 33-year-old man seeking refractive surgery presented with refractive error of -1.75 -4.0×20° in the right and -0.75 -2.5×170° in his left eye in January 2009; best spectacle-corrected visual acuity (BSCVA) was 20/25+ and 20/20- respectively. All ocular examinations were unremarkable and family history for keratoconus was negative. He had previously obtained consultation for refractive surgery in 2000; at that time, intervention had been withheld due to unspecified concerns.

A 15-month-old boy was referred to the Oculo-plastic Clinic at Labbafinejad Medical Center for treatment of a bulging and deformed blind left eye. He was the result of a normal full-term pregnancy and there had been no ocular dis-charge at birth. Examination of the left eye re-vealed a keratinized and ectatic cornea bulging 9 mm anteriorly (Fig. 1). The right eye had a chorioretinal coloboma. Due to severe defor-mity of the blind eye, we considered enuclea-tion to be the most appropriate treatment.

Retinopathy of prematurity is a potentially blinding condition. In this article we describe the surgical management for advanced stages of the disease (stages 4 and 5). Indications, options and alternative techniques are described through a review of articles and our personal experience.

The efficacy of drug delivery to the posterior segment by systemic, local or topical routes is hindered by the blood-retinal barrier, tight intercellular junctions and scantly vascularized spaces. Although intravitreal injection has proved effective for delivery of therapeutic agents into the vitreous cavity and retina, it is impractical for frequent or sustained dosing. Intravitreal sustained release implants offer longterm pharmacotherapeutic exposure to the posterior segment. This novel method bypasses ocular barriers, avoids systemic complications and improves compliance.