Juan J. Arentsen

Results of the Prospective Evaluation of Radial Keratotomy (PERK) Study One Year After Surgery

The Prospective Evaluation of Radial Keratotomy (PERK) study is a nine-center, self-controlled clinical trial of a standardized technique of radial keratotomy in 435 patients who had physiologic myopia with a preoperative refraction between -2.00 and -8.00 diopters. The surgical technique consisted of eight incisions using a diamond micrometer knife with blade length determined by intraoperative ultrasonic pachymetry and the diameter of central clear zone determined by preoperative refraction. At one year after surgery, myopia was reduced in all eyes; 60% were within +/- 1.00 diopter of emmetropia; 30% were undercorrected and 10% were overcorrected by more than 1.00 diopter (range of refraction, -4.25 to +3.38 D). Uncorrected visual acuity was 20/40 or better in 78% of eyes. The operation was most effective in eyes with a refraction between -2.00 and -4.25 diopters. Thirteen percent of patients lost one or two Snellen lines of best corrected visual acuity. However, all but three eyes could be corrected to 20/20. Ten percent of patients increased astigmatism more than 1.00 diopter. Disabling glare was not detected with a clinical glare tester, but three patients reduced their driving at night because of glare. Between six months and one year, the refraction changed by greater than 0.50 diopters in 19% of eyes.

Three-year Results of the Prospective Evaluation of Radial Keratotomy (PERK) Study

The Prospective Evaluation of Radial Keratotomy (PERK) study is a nine-center clinical trial of a standardized technique of radial keratotomy in 435 patients who had simple myopia with a preoperative refractive error between -2.00 and -8.00 diopters (D). We report results for one eye of each patient. The surgical technique consisted of eight incisions using a diamond micrometer knife with the blade length determined by intraoperative ultrasonic pachymetry and the diameter of the central clear zone determined by the preoperative refractive error. At three years after surgery, 58% of eyes had refractive error within one diopter of emmetropia; 26% were undercorrected, and 16% were overcorrected by more than one diopter. Uncorrected visual acuity was 20/40 or better in 76% of eyes. The operation was more effective in eyes with a preoperative refractive error between -2.00 and -4.37 diopters. Between one and three years after surgery, the refractive error changed by 1.00 diopter or more in 12% of eyes, indicating a lack of stability in some eyes.

Factors Associated with Conjunctival Intraepithelial Neoplasia: A Case Control Study

Familial and environmental factors may play a role in the development of conjunctival intraepithelial neoplasia (CIN). Nineteen patients with biopsy-proven CIN completed a questionnaire to evaluate possible predisposing factors. Nineteen age-matched and sex-matched controls completed questionnaires and received slit-lamp examinations. Factors associated with a relatively increased risk of developing CIN included exposure to petroleum products, heavy cigarette smoking, light hair and ocular pigmentation, and family origin in the British Isles, Austria or Switzerland. Non-office and nonprofessional workers were more likely to develop conjunctival intraepithelial neoplasia (p = .05), as were those who were not college graduates (p = .07).

Anterior Stromal Puncture for Recurrent Erosion: Further Experience and New Instrumentation

Anterior stromal puncture has recently been proposed as a new treatment for recalcitrant cases of recurrent corneal erosion. Concerns about the risks of corneal perforation and scarring, as well as doubts regarding its efficacy have prevented many patients from benefiting from this procedure. We introduce a new, inexpensive, commercially available instrument designed to standardize this technique, minimize scarring, and prevent corneal perforation. In a clinical trial involving 25 consecutive patients with recurrent erosions resistant to vigorous conservative treatment, the first 11 patients underwent stromal puncture in which a straight tuberculin needle was used; the following 14 were treated with a newly designed prototype needle. All patients in this series remained free of erosions after completion of stromal puncture, except for one woman with marked diffuse anterior basement membrane dystrophy, who went on to develop spontaneous bilateral erosions. Follow-up ranged from 2 months to 30 months (mean, 13 months). There were no complications of stromal puncture, and subjective and objective evaluations revealed no significant postoperative glare. Microscopic analysis of eye bank eyes subjected to anterior stromal puncture procedures demonstrated that the new prototype needle provided shallower penetration and thus less likelihood of perforation or excessive scarring than the straight needle. Also, postoperative discomfort and scarring appeared to be significantly less in patients treated with the prototype needle.

Pseudophakic bullous keratopathy

We reviewed the records of all patients with pseudophakic bullous keratopathy (271 eyes, 251 patients) seen during a six-month period to determine predisposing factors, associated problems, current management, and visual outcome. Pseudophakic bullous keratopathy was associated most frequently with anterior chamber intraocular lenses in general (155 of 271), and with Leiske style lenses in particular (100 of 271). It was associated with a visual acuity of 20/200 or less in 206 eyes and a visual acuity of counting fingers or less in 129 of the eyes at the initial examination. Penetrating keratoplasties had been performed in 189 of the eyes. After penetrating keratoplasty, 108 of 189 of the eyes had a visual acuity of 20/200 or less (mean follow-up, 15 months). Visual acuity improved with longer follow-up, and among patients with a minimum follow-up of two years, 23 of 36 eyes had a visual acuity of 20/100 or better. Most grafts were clear (145 of 189). Pseudophakic bullous keratopathy was associated with marked visual loss, which was permanent despite clear grafts in 29 of 92 eyes followed-up for one year or longer.

Surgical Management of Pseudophakic Corneal Edema: Complications and Visual Results Following Penetrating Keratoplasty

Of 45 eyes with pseudophakic bullous keratopathy, 40 underwent a penetrating corneal transplant. Thirty-six were followed for over six-months post surgically. Preoperative increased intraocular pressure and endothelial dystrophy in the contralateral eye were common findings. The most important factors limiting visual acuity postoperatively were increased intraocular pressure and cystoid macular edema. Although most grafts remained clear, this does not correlate with the final visual outcome in these patients. Eyes in which the IOL was retained had statistically better visual results than eyes in which the IOL was removed because of associated complicating factors.

Corneal Wedge Resection for High Astigmatism Following Penetrating Keratoplasty

Fourteen corneal wedge resections performed between April 1980 and January 1986 at the Wills Eye Hospital were retrospectively reviewed. Mean pre-operative refractive (subjective) astigmatism was 8.13 diopters (D), with a range of 3.75 to 15.0 D. Following wedge resection, the mean residual astigmatism was 3.04 D, with a range of 0 to 5.0 D. Although the mean keratometric astigmatism measurements were generally similar to the astigmatism measured during refraction, there was little correlation between them on a case-by-case basis. Corneal wedge resection appears to remain an effective and moderately predictable technique for managing high astigmatism following penetrating keratoplasty.

Prospective Evaluation of Radial Keratotomy: Photokeratoscope Corneal Topography

Preoperative and postoperative corneascope photographs of 368 myopic patients undergoing radial keratotomy in the Prospective Evaluation of Radial Keratotomy (PERK) study were optically scanned and digitized. A high-resolution scanning system was developed in order to quantify the preoperative and postoperative corneal shape accurately. Careful analysis of the 72 data points in the nine representative rings demonstrated that corneal topography is best represented by radius of curvature from the center to the periphery. The normal myopic cornea flattens approximately +0.28 mm from the center to the periphery, demonstrating the corneas aspheric nature. More highly myopic patients in the PERK population (-4.50 to -8.00 diopters [D]) demonstrated corneas that are 0.08 to 0.10 mm steeper than the less myopic population (-2.00 to -3.12 D). Optical zone, patient age, and gender are all correlated to changes in corneal topography after radial keratotomy. In more myopic populations, men have corneas which are flatter than those of women by 0.09 to 0.11 mm in all rings represented on corneoscopy. Highly myopic males also experience more corneal flattening after 3.0-mm optical zone radial keratotomy. Regardless of the optical zone used in radial keratotomy, the resulting corneal topography flattens in all rings. However, the ratio of millimeters of radius of curvature change to diopters of correction is consistent for each ring. The dioptric change observed after radial keratotomy corresponds closely with the millimeters of flattening at the respective rings being examined. The central rings flatten 0.166-mm radius of curvature per diopter of refractive alteration obtained. The largest degree of corneal flattening occurs centrally, 0.72 mm, in the more highly myopic patients who underwent 3-mm optical zone radial keratotomy. The use of smaller optical zones in radial keratotomy produces larger changes in the radius of curvature and, consequently, in the amount of refraction than when larger optical zones are used. When compared with younger patients, older patients with 3.0, 3.5, and 4.0 optical zone radial keratotomies experience more central and peripheral corneal flattening. This study of the corneal topography of the myopic population demonstrates that the refractive change resulting from radial keratotomy is related to alterations in corneal topography. The use of similar modifications of the corneal surface may be effective for newer refractive surgical procedures.

Management of Corneal Descemetoceles and Perforations

55 patients (58 yeux) traites par differentes methodes medicales et chirurgicales: lentilles souples, colle chirurgicale, lambeaux conjonctivaux, greffes de cornee, enucleation

Treatment of Neurotrophic Ulcers with Conjunctival Flaps

1. Lee, D. A., Rimele, T. ]., Brubaker, R. F., Nagataki, S., and Vanhoutte, P. M.: Effect of thymoxamine on the human pupil. Exp. Eye Res. 36:655, 1983. 2. Wand, M., and Grant, W. M.: Thymoxamine hydrochloride. An alpha-adrenergic blocker. Surv. Ophthalmol. 25:75, 1980. 3. Brogliatti, B., Rolle, T., Messelrod, M., and Boles Carenini, B.: A new alpha-blocking agent in the treatment of glaucoma. Dapiprazole. Glaucoma 7:232, 1985. 4. Grehn, F., Fleig, T., and Schwarzmuller, E.: Thymoxamine. A miotic for intraocular use. Graefes Arch. Clin. Exp. Ophthalmol. 224:174, 1986.