BACKGROUND: A retrospective observational study was conducted to test the hypothesis that there is clinically measurable epithelial hyperplasia after photorefractive keratectomy (PRK), and to determine its effect on the epithelial oxygen uptake rate. METHODS: One hundred myopic eyes who had been previously treated unilaterally with PRK were examined. Fifty eyes were treated with the Summit excimer laser (Summit Technology, Waltham, Mass) 27 +/- 7 months previously with ablation zone diameters of 4.1, 4.3, 4.5, or 5.0 mm. Fifty eyes were treated with the VISX excimer laser (VISX Inc, Sunnyvale, Calif) 5 +/- 4 months previously with one ablation zone diameter of 6.0 mm. The untreated eyes served as controls. Epithelial thickness was measured at a standardized central area within the ablation zone with a modified optical pachometer. Oxygen uptake rate was measured in a subgroup of 30 eyes (20 Summit and 10 VISX). RESULTS: The epithelium after PRK was 24% thicker than in the control eye in the Summit group (mean difference 13 +/- 10 microns; p < .01) and 7% thinner in the VISX group (mean difference -4 +/- 10 microns; p < .01). A higher oxygen uptake rate correlated with a thicker epithelium (r = 0.42; p < .05). CONCLUSIONS: The epithelium was significantly thicker after PRK between 13 and 37 months after treatment with the Summit excimer laser using ablation zone diameters of 4.1 to 5.0 mm. The epithelium was thinner between 1 and 15 months after treatment with the VISX laser using an ablation zone diameter of 6.0 mm. An increase in oxygen uptake rate reflected the metabolic rate of a greater number of cells in the hyperplastic layer.

Adolescent↗

PubMedDate not supplied

Photorefractive keratectomy for 1.5 to 18 diopters of myopia.

The purpose of this study was to evaluate the refractive outcome and the stability of refraction after excimer laser photorefractive keratectomy (PRK). Forty-five eyes were treated in three different refractive groups: low myopes, 23 eyes, -1.50 diopters (D) to -6.00 D; intermediate myopes, 14 eyes, -6.10 D to -10.00 D; and high myopes, 8 eyes, -10.10 D to -18.00 D. At 9 months after surgery the low myopes had a mean refraction of -0.14 D (range -1.00 D to + 1.50 D) and were easy to refract. Intermediate myopes mean refraction was +0.14 D (range -1.50 D to +2.50 D). In the high myope group the mean refraction was -0.47 D (range -10.00 D to +2.50 D) and four eyes (50%) lost more than two lines of spectacle corrected visual acuity. Refraction the high myopes was more difficult compared to the lower myopes. PRK produced good results for myopes from -1.50 D to -10.00 D. Myopes greater than -10.00D are not stable at 9 months after PRK and are difficult to refract.

Adult↗

PubMedDate not supplied

Patient satisfaction following photorefractive keratectomy for myopia.

This study was conducted to evaluate the subjective response of patients who underwent photorefractive keratectomy (PRK) for myopia with the Summit Technology UV 200 LA excimer laser (Summit Technology, Inc., Waltham, Mass.) (3.5 to 5.0 mm diameter ablation zone) 36 months previously. One-hundred thirteen patients with preoperative myopia between -1.50 diopters (D) and -6.50 D with an ablation diameter of 3.5 mm to 5.0 mm answered a questionnaire at the 36-month examination. Sixty-two percent of patients had both eyes treated. Halo problems were experienced always by 34% of patients in the group, 26% sometimes, and 40% never. Permanent night vision problems were experienced by 40%; 30% reported them sometimes and 30% reported no problems at all. Sixty percent never needed to use glasses after treatment, 30% sometimes did, and 10% always wore glasses. Seventy percent of patients thought the results were very good; the remaining 30% experienced different degrees of halo and night vision problems.

Adult↗

PubMedDate not supplied

Failure of mechanical epithelial removal to reverse persistent hyperopia after photorefractive keratectomy.

BACKGROUND: Residual hyperopic overcorrection after photorefractive keratectomy (PRK) using early algorithms is a rare but serious complication. Anecdotal evidence suggests that epithelial removal can stimulate epithelial hyperplasia, thereby reducing overcorrection. The aim of this study was to determine if epithelial removal effectively reduced hyperopia after PRK for myopia and, concurrently, to correlate the healing response with the refractive outcome. METHODS: Enrolled were seven eyes of seven patients (mean age, 44 +/- 13 years) who had undergone PRK with a mean manifest refractive error of +2.21 +/- 0.74 diopters (D). All had undergone PRK an average of 24 +/- 9 months previously. Epithelial removal was performed over the excimer-treated zone with a surgical blade. Subjective refraction, epithelial thickness, corneal topography, and subepithelial haze were measured up to 1 year postoperatively. RESULTS: Reduction in hyperopia between the baseline and 1-year visit was not statistically significant (mean difference, 0.55 D reduction; p = .102). That epithelial removal did not stimulate a wound-healing response is further supported by the absence of change in epithelial thickness over the first month and the small amounts of subepithelial haze. Central corneal power was reduced by a mean of 0.64 D after 1 month (p < .05). CONCLUSIONS: Epithelial removal alone did not reduce the hyperopic overcorrection present after PRK, nor did it stimulate epithelial hyperplasia in the majority of these eyes. However, a trend toward improvement was noted with time was noted.

Adult↗

PubMedDate not supplied

Effect of corticosteroids in postoperative care following photorefractive keratectomies.

Since the start of photorefractive keratectomy (PRK) Seiler has recommended the use of topical corticosteroids during the first 3 months after surgery. The rationale for this treatment was to diminish the inflammatory reaction as well as to control the keratocytes from producing collagen and creating scars. Our knowledge of corneal wound healing in general, and after PRK in particular, is very limited and the action of corticosteroids is still unclear. Corticosteroids, when given in comparatively large topical doses, create problems. Between 15 and 30% of patients are corticosteroid responders with increased intraocular pressure. This is a threat to the eye, and also a burden for the doctor as intraocular pressure has to be checked during the treatment. The risk for cataract formation after longer periods of topically administered corticosteroids also has been discussed. In order to decrease the rise in intraocular pressure, FML has been used in place of dexamethasone. During the 4 years follow up after PRK it has been reported that a number of patients do not regress or get a scar formation if they have not used corticosteroids in the postoperative period. The reasons to avoid topical corticosteroids in some patients are a misunderstanding of their instructions, or those who have had a history of herpes infection or glaucoma. A double-masked study of the effects of corticosteroids after PRK was performed by Gartry, et al in a small group of patients. After 6 months, the results revealed that there were no differences between the corticosteroid and the non-corticosteroid group. However, the standard deviation was high.(ABSTRACT TRUNCATED AT 250 WORDS)

Cornea↗

PubMedDate not supplied

Phototherapeutic keratectomy: long-term results in 166 eyes.

One hundred sixty-six eyes with corneal disease were treated with the excimer laser in order to ablate opacities, irregularities, or to improve wound healing. Postoperative follow up time was 15 months (range 6 to 28 months). An individual goal was set for each patient and 84% achieved the goal. The visual acuity change is given for each subgroup. Phototherapeutic keratectomy (PTK) was shown to be an advantageous surgical method, where the success is in the careful preoperative evaluation. One problem with the technique is the induced hyperopia.

Adult↗

PubMedDate not supplied

Radiographic exophthalmometry.

Radiographic exophthalmometry is based on the simultaneous exposure of a radiograph and a photograph. The fixed reference point for both eyes is the tuberculum sellae, which is a midline structure. Eye position is correlated with skull size and race to provide a sensitive detection of exophthalmos. A statistically significant difference in the position of the eyes in US black and white people has been found to exist. No difference in the position of left or right eyes has been found in either US black or white people.

Black or African American↗

PubMedDate not supplied

Localization of intraorbital foreign bodies: an improved photoradiographic method.

A previously described photoradiographic camera used to localize intraocular or intraorbital foreign bodies has been modified to a more versatile unit. One photograph and one radiograph are taken simultaneously, and the pictures are combined, whereby the eye appears as its own indicator on the radiophotograph. More than 50 foreign bodies have been successfully localized with the camera which is easy to handle and can be used in any x-ray film room where an overhead tube is available.

Eye Foreign Bodies↗