Felix N. Sabates

Excimer photorefractive keratectomy for myopia

PURPOSE To study the safety, effectiveness, predictability, and stability of excimer laser photorefractive keratectomy (PRK) in 133 normally sighted eyes. METHODS An excimer laser was used with a fluence of 160 mJ/cm2 at a frequency of 5 Hz and an ablation zone of 5.0 mm. The effects of nitrogen purge at surgery and postoperative steroids were evaluated. RESULTS No significant complications occurred in any patient. After an initial over-correction, the refraction stabilized. The average results obtained at 6 months were maintained on successive examinations to 36 months. Analysis of their visual acuity in groups IIA, IIB, and III indicates that results at 6 months are predictive of final results at 1 to 3 years (P < 0.0001; r > 0.9). In myopia (1.00-6.00 diopters [D]) treated with the excimer laser, there was a trend toward improvement in results over the course of the study. In 60% in group IIA, 58% in group IIB, 71% in group III, and 88% in group III no nitrogen (no N2), +/- 1 D was obtained. For 20/40 or better uncorrected visual acuity, the outcome was 70% for group IIA, 67% for group IIB, 75% for group III, and 100% for group III no N2. Significant improvement was noted without nitrogen purge. No significant improvement was observed from steroid treatment as used. CONCLUSION In reducing myopia, PRK appears to be safe and effective. The results obtained are reasonably predictable and stable after 6 months. As more refinements are introduced, this procedure could become one of the most promising in refractive surgery.

Macular Changes After Retinal Detachment Surgery

We studied 175 eyes of 175 patients who had successful repair of primary rhegmatogenous retinal detachment. Patients were randomly assigned to be treated with cryotherapy and episcleral sponges or with diathermy, scleral dissection, and encircling silicone bands. Fundus photography and fluorescein angiography were performed six weeks after successful reattachment surgery. Macular complications were discovered in 48 (27%) of the 175 eyes. The most frequent changes were cystoid macular edema in 28 (16%) and preretinal macular membrane in 13 eyes (8%). No significant differences in the incidence of cystoid macular edema were observed between diathermy and cryotherapy. Macular detachment, increased duration of macular detachment, cryotherapy, and pseudophakia were identified as risk factors for certain macular complications.

Laser treatment in fellow eyes with large drusen: Updated findings from a pilot randomized clinical trial

PURPOSE To update the findings from the Choroidal Neovascularization Prevention Trial (CNVPT) with respect to resolution of drusen, incidence of choroidal neovascularization, and visual function. DESIGN A multicenter, randomized, controlled, pilot clinical trial. PARTICIPANTS The 120 patients enrolled in the CNVPT. Patients had signs of choroidal neovascularization or retinal pigment epithelial detachment in 1 eye and had >/=10 large (>63- micro m) drusen in the contralateral, or fellow, eye. INTERVENTION The fellow eye of 59 patients was assigned randomly to argon green laser treatment consisting of multiple 100- micro m spots at least 750 micro m from the center of the fovea. The fellow eye of the remaining 61 patients was assigned randomly to observation. MAIN OUTCOME MEASURES Change in visual acuity was the primary outcome measure. Incidence of choroidal neovascularization, resolution of drusen, change in contrast threshold, change in critical print size for reading, and incidence of geographic atrophy were secondary outcome measures. RESULTS Throughout 4 years of follow-up, there were no statistically significant differences in change in visual acuity, contrast threshold, critical print size, or incidence of geographic atrophy. With additional follow-up, the large increase in the incidence of choroidal neovascularization observed within 18 months of treatment was maintained; however, by 30 months, the incidence in the two treatment groups was the same. Most drusen resolution in treated eyes occurred within 24 months of the initial treatment. Treated eyes that received higher-intensity laser burns had an increased risk of choroidal neovascularization. Among eyes developing choroidal neovascularization in each treatment group, most lesions (two thirds or more) were composed of occult neovascularization only. CONCLUSIONS Laser treatment as applied in the CNVPT caused an excess risk of choroidal neovascularization in the first year or so after treatment. The increased early incidence of choroidal neovascularization was not associated with either a harmful or beneficial effect in this pilot study.

A Comparative Study of Argon and Krypton Laser Photocoagulation in the Treatment of Presumed Ocular Histoplasmosis Syndrome

Ninety eyes from 88 patients with active macular subretinal neovascular membranes of presumed ocular histoplasmosis were treated with photocoagulation: 45 eyes with blue-green argon laser and 45 with red krypton laser. Final visual results are compared between these two series and natural course of the disease. The krypton laser photocoagulated eyes obtained better final visual results when compared with both the argon laser treated series and natural course.

Lymphoma of the Vitreous Associated with Renal Transplantation and immunosuppressive Therapy

A renal transplant patient presented with a uveitis unresponsive to high doses of steroids. A pars plana vitrectomy was performed for diagnosis. Light and transmission electron microscopy confirmed the diagnosis of lymphoma of the vitreous. Six percent of the renal transplant recipients develop tumors. This frequency is 100 times greater than the general population. Reticulum cell sarcoma is the predominant type being 350 times more common in renal transplant recipients than in the general population. The patient was taking immunosuppressive drugs which depress the immunologic surveillance. Antigenic neoplastic cells may arise by somatic mutations and may proliferate producing neoplasms with loss of the surveillance mechanism. The case presented illustrates that persons immunosuppressed may develop an eye tumor presenting as uveitis.

Scanning laser ophthalmoscope macular perimetry in the evaluation of submacular surgery.

PURPOSE Submacular surgery for choroidal neovascularization (CNV) is under investigation in the treatment of age-related macular degeneration (AMD) and the presumed ocular histoplasmosis syndrome. Four case studies are presented to demonstrate scanning laser ophthalmoscope (SLO) testing in the pre- and postsurgical evaluation of visual function in patients with subfoveal CNV secondary to AMD, presumed ocular histoplasmosis syndrome, and submacular hemorrhage secondary to AMD. METHODS Patients underwent a visual assessment pre- and 6 months postoperatively, consisting of low vision visual acuity measurement, SLO macular perimetry of dense and relative scotomas, and analysis of the preferred retinal locus for fixation (PRL) location and ability. RESULTS Visual acuity, dense and relative scotoma size and location, and PRL location were compared; and relationships between anatomic and functional changes were observed. Decreases in scotoma size and improvement in PRL location and ability usually corresponded with improved visual acuity. Preoperative scotoma and PRL location guided retinotomy site selection. CONCLUSION Scanning laser ophthalmoscope macular perimetry and PRL testing may be useful adjuncts in the visual assessment of submacular surgery and may advance under-standing of the effects of submacular surgery on visual function. In addition, this testing may be used to plan location of surgical interventions for macular diseases.

Early Argon Laser Photocoagulation of Presumed Histoplasma Maculopathy

In this study, 66 patients with presumed ocular histplasmic maculopathy and in whom the edge of the neovascular membrane was at least 200 micron from the center of the fovea were selected for treatment with argon laser photocoagulation. They were divided into three groups depending on the time elapsed between the beginning of symptoms and treatment with argon laser photocoagulation. The size of the neovascular membrane, the distance from the center of the fovea, and the presence of hemorrhage in the foveal area were also noted. We found that the most important prognostic factor for best final visual acuity was the interval of time between onset of symptoms and treatment. The study showed that 73.3% (22 of 30) of patients with symptoms of short duration (four weeks or less) compared with 17.6% of those with symptoms of long duration (16 weeks or more) retained 6/15 (20/50) or better final visual acuity following argon laser photocoagulation treatment.

Clinical application of optical coherence tomography in combination with functional diagnostics: advantages and limitations for diagnosis and assessment of therapy outcome in central serous chorioretinopathy

Purpose While identifying functional and structural parameters of the retina in central serous chorioretinopathy (CSCR) patients, this study investigated how an optical coherence tomography (OCT)-based diagnosis can be significantly supplemented with functional diagnostic tools and to what degree the determination of disease severity and therapy outcome can benefit from diagnostics complementary to OCT. Methods CSCR patients were evaluated prospectively with microperimetry (MP) and spectral domain optical coherence tomography (SD-OCT) to determine retinal sensitivity function and retinal thickness as outcome measures along with measures of visual acuity (VA). Patients received clinical care that involved focal laser photocoagulation or pharmacotherapy targeting inflammation and neovascularization. Results Correlation of clinical parameters with a focus on functional parameters, VA, and mean retinal sensitivity, as well as on the structural parameter mean retinal thickness, showed that functional measures were similar in diagnostic power. A moderate correlation was found between OCT data and the standard functional assessment of VA; however, a strong correlation between OCT and MP data showed that diagnostic measures cannot always be used interchangeably, but that complementary use is of higher clinical value. Conclusion The study indicates that integrating SD-OCT with MP provides a more complete diagnosis with high clinical relevance for complex, difficult to quantify diseases such as CSCR.

Management of Acute Ocular Histoplasmosis Syndrome

In summary, there are various factors which play an important prognostic role in the final visual acuity of patients with active histoplasma maculopathy. The factors over which we have no control is the location of the neovascular membrane in this maculopathy. The factors over which we do have control are how and when to treat it. We feel that laser photocoagulation is an effective method of treatment. It has been possible to obliterate the NVM as close as 200 micrometers from the foveola, thus preventing the development of subfoveal NVMs which have such a poor visual prognosis. The most important factor is the early treatment with laser photocoagulation. If we could treat all patients within 4 weeks of initial visual symptoms (group A), we might be able to eliminate a large number of patients (group C) who have a much poorer visual prognosis. Serial postoperative fluorescein studies are necessary to detect recurrent neovascular membranes which require further treatment.