Peter J Agapitos

Laser vision correction for low hyperopia. An 18-month assessment of safety and efficacy.

OBJECTIVE This study aimed to assess the efficacy and safety of hyperopic photorefractive keratectomy (PRK) and to evaluate the effect of degree of hyperopia, two epithelial removal methods, and various postoperative patient management techniques on clinical outcomes. DESIGN Prospective, nonrandomized, open-label clinical trial. PARTICIPANTS A total of 38 patients with mean follow-up of 13.9 months (n = 65 eyes with hyperopia from +1.00 diopter [D] to +4.00 D) participated. INTERVENTION Hyperopic PRK with the VISX STAR Excimer Laser System was performed. MAIN OUTCOME MEASURES Spherical equivalent (SE) including vector analysis of SE; uncorrected visual acuity (UCVA); best-spectacle corrected visual acuity (BSCVA); low-, medium- and high-contrast visual acuities; topography; keratometry; pachymetry; and intraocular pressure, haze, and all other potential complications were measured. RESULTS A total of 80% of eyes were within +/- 0.5 D and all but 1 eye (98%) were within +/- 1.0 D of intended manifest SE at 1 year. There was no induced astigmatism at 1 year. At 12 months, 72% of eyes had UCVA of 20/25 or better and 70% had achieved preoperative BSCVA, with no eye seeing worse than 20/25. These results remained constant at 18 months. There was a tendency toward regression between months 1 and 6 with stabilization of SEs between months 6 and 12. Thereafter, up to 18 months, there was some regression with a mean of +0.31 D, but the number of patients was small. There was one mild decentration and very slight decreases in mean intraocular pressure and central corneal thickness. One patient had grade 1.0 haze develop in both eyes at 12 and 18 months; all other patients experienced trace or no haze. There were no significant complications. CONCLUSIONS The results of this study support the hypothesis that laser vision correction is safe and effective for treating low hyperopia. The predictability of the hyperopic laser vision correction procedure used in this study was very good. Other than the slower recovery of BSCVA and UCVA seen with this procedure, as compared with myopic PRK, there were no significant complications. The trend toward some later regression needs to be further evaluated in a larger number of patients. Overall, patients were very pleased with the treatment, even in the first 6 months.

Intrastromal corneal ring segments for low myopia: a report by the American Academy of Ophthalmology.

OBJECTIVE This document describes intrastromal corneal ring segments (Intacs) inserts technology and examines the evidence to answer the key question about whether the treatment is safe and effective in correcting low myopia. METHODS A literature search that was conducted in September 2000 retrieved 13 relevant citations, and the reference lists of these articles were consulted for additional citations. Panel members reviewed this information and articles were rated according to the strength of evidence. RESULTS Prospective multicenter phase II and III clinical trials (Level II evidence rating) of Intacs inserts for myopia of -1.00 to -3.00 diopters (D), with a maximum of +1.00 D of astigmatism, enrolled a total of 452 subjects, with a total of 454 surgical attempts. The results from phase II and phase III were pooled for much of the analysis. At 1 year, 97% of patients who completed follow-up had 20/40 or better uncorrected visual acuity (UCVA). Seventy-four percent of patients had 20/20 or better UCVA. Ninety-two percent of eyes were within +/-1 D of intended refractive correction, and 69% were within 0.5 D of intended refractive correction. At 3 months, 90% of patients had less than 1.0 D of change from the previous examination performed at 1 month. The ocular complication rate, which was defined as clinically significant events but not resulting in permanent sequelae, was 11% at 12 months. The adverse event rate was 1.1%, defined as a serious event if untreated. Nearly 9% of patients requested to have their inserts removed and a total of 3.8% of patients required a secondary surgical intervention. CONCLUSIONS To date, evidence suggests that low myopia (-1 to -3 D) in a well-defined group of patients who have a stable manifest refraction and less than +1.0 D of astigmatism can be treated with Intacs inserts with a reasonable assurance of safety and effectiveness. Additional clinical research is needed to determine the long-term effectiveness of treatment and the comparative safety, effectiveness, and costs with other treatment modalities, including laser-assisted in-situ keratomileusis (LASIK) and photorefractive keratectomy (PRK).

Evaluation of current techniques of corneal epithelial removal in hyperopic photorefractive keratectomy

Purpose: To determine the efficacy of 3 current methods used to remove corneal epithelium prior to photorefractive correction of hyperopia and to compare clinical data in patients who had rotary brush or blunt scrape epithelial removal in the treatment of hyperopic photorefractive keratectomy (PRK). Setting: University of Ottawa Eye Institute, Ottawa General Hospital, Ottawa, Ontario, Canada. Methods: The epithelium from human eye‐bank eyes was removed using a Paton spatula, 15% alcohol, and the Amoils rotating plastic brush. The effects were examined by scanning and transmission electron microscopy. Twelve month postoperative data were obtained on 25 eyes with refractions of +1.00 to +4.00 diopters (D) that had been treated for hyperopia with the VISX Star excimer laser, using blunt scrape or the rotary brush to remove the corneal epithelium. Results: All 3 methods effectively removed corneal epithelium. The Paton spatula, however, left small nicks in Bowman’s layer. Both the rotating brush and alcohol debridement left Bowman’s layer intact. Alcohol treatment required follow‐up epithelial debris removal, while brushing left minimal amounts of debris. There was a strong trend toward rapid epithelial healing in the brushed corneas compared with the scraped ones, but this was not statistically significant. Clinically, at 12 months postoperatively, brushed corneas showed a trend toward more superior outcomes than scraped corneas in actual refractive outcome, uncorrected visual acuity (UCVA), lines of UCVA gained, and predictability of the desired outcomes. However, only the outcome in UCVA of 20/40 or better and the decreased incidence of haze in the brushed corneas over scraped ones were statistically significant. Conclusions: Both alcohol and the rotating brush provide a quick, effective means of removing the corneal epithelium with minimal risk of damage to Bowman’s layer. In our experience, the brush technique was as effective as and possibly superior to the blunt scrape for epithelial removal in hyperopic PRK.

Excimer laser photorefractive keratectomy for low hyperopia: Safety and efficacy

Purpose: To assess the safety and efficacy of photorefractive keratectomy (PRK) to correct low hyperopia. Setting: University of Ottawa Eye Institute, Ottawa General Hospital, Ontario, Canada. Methods: Twenty‐five eyes with refractions of +1.00 to +4.00 diopters (D) and cylinder of 1.00 D or less were treated for hyperopia with the VISX Star excimer laser system using a refined ablation architecture. Thorough visual assessments were performed preoperatively (baseline) and 1, 3, and 6 months postoperatively. Complications were recorded and the level of patient satisfaction was noted. Results: Mean spherical equivalent at 6 months was +0.27 D ± 0.55 (SD), which was an 89% reduction over baseline. Eighty‐four percent of patients gained two to seven lines of near uncorrected visual acuity (UCVA) and 1 patient (4%) lost more than one line. Eight percent achieved 20/25 or better UCVA. Approximately half realized their preoperative distance best corrected visual acuity (BCVA) by 1 month. By the end of the study, all patients had improved, achieved, or were within one line of their baseline distance BCVA. There were some slight reductions in lower contrast acuity at 6 months, although dim lighting conditions did not further reduce these acuities. Most patients had no clinically meaningful change in cylinder. The most common complications included early, transient corneal surface irregularities and visual symptoms and trace haze (grade ≤0.5) in 14 of 23 patients at 6 months. All but 1 patient expressed a high degree of satisfaction. Conclusions: These results support the hypothesis that PRK shows great promise as a safe and effective treatment for low hyperopia. There were no significant complications and no decentered ablations. The slight regression occurred with or without the presence of trace haze. Overall, refractive stability was encouraging, although longer follow‐up is needed.

Ruptured Globe After Radial Keratotomy

acid treatment was immediately stopped and two months later the corneal calcification disappeared. Favorable results of topical retinoic acid therapy for disorders of the outer eye have been reported, with local irritation noted as the only side effect. Topical vitamin A treatment was also found to increase the healing of cataract incisions. Patients with dry eye syndrome who are treated with retinoic acid should be followed up carefully to watch for this possible side effect.

Four-incision radial keratotomy for high myopia after penetrating keratoplasty

BACKGROUND High amounts of myopia can frequently produce anisometropia and limit visual rehabilitation by conventional means in eyes with clear corneal grafts. This condition is frequently coupled with large amounts of astigmatism. Four-incision radial keratotomy provides a way to reduce myopia in normal individuals. In our present study, we used the technique of four- incision radial keratotomy to reduce myopia in a group of keratoplasty patients who failed conventional visual rehabilitation. Arcuate or transverse keratotomy was used in conjunction with radial keratotomy in eyes with high amounts of astigmatism. METHODS This study retrospectively examined a group of 11 eyes with penetrating keratoplasty which underwent four-incision radial keratotomy for the treatment of visually disabling myopia. The radial incisions were placed in the graft, inside the graft-host interface. Seven eyes underwent concomitant arcuate relaxing incisions at the graft-host interface for treatment of associated astigmatism. One additional eye had paired straight transverse incisions for the treatment of astigmatism. The mean postoperative follow up was 16 months (range, 3 months to 5 years). RESULTS There was a mean reduction of the spherical equivalent refraction of 3.48 diopters (D) (range, 0.25 to 7.75 D). The eight eyes undergoing astigmatic surgery showed a mean reduction in keratometric astigmatism of 2.25 D (range, -6.75 to +6.50 D) and refractive astigmatism of 4.63 D (range, -1.50 to -9.50 D). Nine of the 11 eyes had stable or improved best spectacle corrected visual acuity. Two eyes had reduction of best spectacle corrected visual acuity--one due to development of irregular astigmatism and one due to worsening of preexisting macular edema. CONCLUSIONS Four-incision radial keratotomy can reduce myopia after penetrating keratoplasty when the patient is unable to tolerate spectacle or contact lens correction. It can be combined with relaxing incisions or transverse keratotomy to reduce astigmatism. There is a high amount of variability, and predictability is currently limited by the complex topographical changes occurring in corneal transplants. Complex corneal biomechanical changes may predispose these eyes to the development of irregular astigmatism.

Ultrastructural Features of Posterior Crocodile Shagreen of the Cornea

Three elderly patients with a clinical diagnosis of posterior crocodile shagreen of the cornea underwent penetrating keratoplasty. Each of the patients had the characteristic symmetrical, polygonal opacities with indistinct edges and intervening clear spaces in the central posterior corneal stroma. Electron microscopic examination of the keratoplasty specimens disclosed the presence of vacuoles throughout the corneal stroma, many of which contained electron-dense material. The vacuoles were observed with increasing density posteriorly and were most concentrated adjacent to the anterior banded portion of Descemets membrane. A sawtooth-like configuration of the stromal collagenous lamellae was noted in the posterior cornea in one case. We reviewed the three cases of central corneal clouding reported with histopathological findings as well as the clinical descriptions of this entity. Although a sawtooth-like lamellar configuration of the stromal collagen may be seen by electron microscopy, characteristic vacuoles appear to be the only consistent finding. We believe that posterior crocodile shagreen is most likely a degenerative disorder and that it should be distinguished from central cloudy dystrophy of François by its non-familial pattern of occurrence.

Ocular Findings in Acromesomelic Dysplasia

We examined an infant who had prenatal onset of a skeletal dysplasia that had many features in common with acromesomelic dysplasia, including the clinical and light and electron microscopic findings of both corneas. Successful lamellar keratoplasty was performed on the left eye when histologic examination of the corneal button from the right eye showed that the corneal scar was only of partial thickness.