Richard L. Lindstrom

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.

Keratoconus and Corneal Ectasia After LASIK

From Gordon Binder Weiss Vision Institute, San Diego, Calif (Binder); Minnesota Eye Consultants, Minneapolis, Minn (Lindstrom); Emory University, Atlanta, Ga (Stulting); Ophthalmic Consultants of Long Island, Rockville Centre, NY (Donnenfeld); Tufts New England Medical Center, Boston, Mass (Wu); Wilmer Ophthalmological Institute, Johns Hopkins University School of Medicine, Baltimore, Md (McDonnell); and Cornea Genetic Eye Institute, Cedars Sinai Medical Center, Los Angeles, Calif (Rabinowitz).

CORNEOSCLERAL MELT AFTER PTERYGIUM SURGERY USING A SINGLE INTRAOPERATIVE APPLICATION OF MITOMYCIN-C

A 59-year-old man underwent pterygium excision with intraoperative application of 0.2 mg/ml (0.02%) mitomycin-C placed on the scleral bed for 3 min. A sliding conjunctival flap was used to cover the exposed limbus and sclera. Five weeks after the original surgery, the patient had mild trauma and noted decreased vision. At that time, it was noted that he had a corneoscleral melt with perforation. The patient was managed with a lamellar transplant in this area. Intraoperative single-dose application of topical mitomycin-C can be associated with serious complications. This case occurred despite the fact that this patient received the lowest dose used in a series of 25 eyes using the same technique without any other complications. Although topical mitomycin-C is effective as an adjunct to pterygium surgery and may reduce recurrence, the safety and efficacy of various concentrations and dosing schedules need further definition.

Excimer Laser Photorefractive Keratectomy in High Myopia: A Multicenter Study

Excimer photorefractive keratectomy was performed at three centers on 16 highly myopic eyes (8 diopters [D] or more) and followed up for 6 months. Ablation depths ranged from 137 to 230 microns. The preoperative spherical equivalent of myopia ranged from -8.62 D to -14.50 D (mean +/- SD, -11.57 +/- 1.62 D). Six months after surgery, the mean refraction (spherical equivalent) was -0.90 +/- 2.13 D. Eleven of 16 eyes achieved refractions within 2 D of that attempted. All eight patients at one site were treated with a maximum-beam diameter of 6.0 mm and were corrected to within 2 D of that attempted, and all were 20/40 or better uncorrected. Three of eight eyes at the other two sites were treated with a 5.5- or 5.6-mm maximum-beam diameter, which achieved corrections within 2 D of that attempted. The epithelium healed within 3 to 4 days, and there were no erosions. Mild subepithelial reticular haze, similar to that seen with excimer photorefractive keratectomy for lower myopia, was seen in all patients, with two patients experiencing more significant corneal haze. This peaked at 3 to 6 weeks and then gradually diminished. All but two patients had a return of their best corrected preoperative visual acuity to within one Snellen line at 6 months. This preliminary study shows excimer photorefractive keratectomy to be a promising surgical treatment for patients with higher myopia.

Anatomic Study of Transsclerally Sutured Intraocular Lens Implantation

We used 21 cadaver eyes to study transsclerally sutured, ciliary sulcus-fixated intraocular lens implantation. Results showed that transscleral sutures should exit the sclera less than 1 mm posterior to the corneoscleral limbus for true ciliary sulcus fixation. The relationship of the ciliary sulcus to the overlying posterior surgical limbus differed in the vertical and horizontal meridians; needles that pierced the ciliary sulcus after being passed perpendicularly through the sclera entered the sclera 0.83 +/- 0.1 mm posterior to the posterior surgical limbus in the vertical meridians and 0.46 +/- 0.1 mm in the horizontal meridians. The major arterial circle of the iris (located in the ciliary body) was avoided as was the entire ciliary body during proper ciliary sulcus fixation. A one-piece, all polymethylmethacrylate, 10-degree vaulted, 13.5-mm haptic spread intraocular lens provides excellent optic centration and haptic stabilization when the haptic structure is placed at the greatest haptic spread and one transscleral suture pass per haptic is made.

Long-term effects of phacoemulsification with intraocular lens implantation in normotensive and ocular hypertensive eyes

PURPOSE: To evaluate the long‐term effect of phacoemulsification with intraocular lens (IOL) implantation alone in normotensive and ocular hypertensive eyes. SETTING: Private practices, Minneapolis, Minnesota, and Savannah, Georgia, USA. METHODS: The IOP before surgery, 1 year after surgery, and at the final chart recording in 588 eyes having phacoemulsification with IOL implantation was retrospectively reviewed. Before surgery, eyes were divided into 5 groups based on IOP at surgery, patient age at surgery, years of postoperative follow‐up, and a comparison between IOP at 1 year and IOP at the final check. RESULTS: The final mean IOP reduction was 6.5 mm Hg (27%) in the 31 to 23 mm Hg presurgical IOP group (n = 19), 4.8 mm Hg (22%) in the 22 to 20 mm Hg group (n = 62), 2.5 mm Hg (14%) in the 19 to 18 mm Hg group (n = 86), and 1.6 mm Hg (9%) in the 17 to 15 mm Hg group (n = 223). In the 14 to 9 mm Hg group (n = 198), the mean IOP at the final examination was 0.2 mm Hg higher (0.1% increase). CONCLUSIONS: Stratifying eyes according to presurgical IOP showed greater long‐term IOP reductions than previously reported. The reduction was proportional to the presurgical IOP. The decrease was greatest in eyes with the highest presurgical IOP. The IOP remained unchanged in eyes with the lowest presurgical IOP. The IOP reductions at 1 year were sustained over 10 years and were similar in patients of all ages.

Intraocular pressure reduction after phacoemulsification with intraocular lens implantation in glaucomatous and nonglaucomatous eyes: Evaluation of a causal relationship between the natural lens and open-angle glaucoma

PURPOSE: To study the long‐term effects of phacoemulsification with intraocular lens (IOL) implantation in nonglaucomatous and glaucomatous eyes. SETTING: Phillips Eye Institute, Minneapolis, Minnesota, and private practice, Savannah, Georgia, USA. METHODS: Intraocular pressure (IOP) after phacoemulsification with IOL implantation was retrospectively reviewed. Eyes were divided into 5 groups by preoperative IOP. Data were recorded preoperatively, 1 year postoperatively, and at the final check. Analysis included preoperative IOP versus IOP at 1 year and final IOP, percentage of eyes with elevated or reduced IOP postoperatively, patient age at surgery, and years of postoperative follow‐up. RESULTS: The study comprised 124 eyes. The final mean IOP reduction was 8.5 mm Hg (34%) in the 29 to 23 mm Hg group, 4.6 mm Hg (22%) in the 22 to 20 mm Hg group, 3.4 mm Hg (18%) in the 19 to 18 mm Hg group, and 1.1 mm Hg (10%) in the 17 to 15 mm Hg group. In the 14 to 5 mm Hg group, IOP increased by 1.7 mm Hg (15%). CONCLUSIONS: Intraocular pressure reduction was proportional to preoperative IOP; the highest preoperative IOPs decreased the most and the lowest increased slightly. One‐year IOP reductions were sustained for 10 years and were similar in patients of all ages. The IOP reductions were similar to previously reported reductions in nonglaucomatous eyes, indicating that the aging crystalline lens may be a major cause of ocular hypertension and glaucoma and that phacoemulsification with IOL implantation may help prevent and treat adult glaucoma.

Optisol Corneal Storage Medium

Optisol is an investigational, intermediate-term corneal storage medium containing chondroitin sulfate and dextran to enhance corneal dehydration during storage. We used scanning electron microscopy to grade endothelial cell morphologic characteristics in terms of cell shape, cell borders, cell swelling, and apical holes in pairs of corneas stored in Optisol and Dexsol. Optisolstored corneas showed significantly fewer morphologic changes after 14 days at 4 degrees C than did Dexsol-stored corneas. No significant differences were seen after 1 to 4 days at 26 degrees C. Temperature-reversal analysis showed no significant change in corneal thickness with warming after 2-week storage at 4 degrees C in either medium, although Optisol-stored corneas were significantly thinner than those stored in Dexsol at all times. The results of scanning electron microscopy suggest that preservation at refrigerator temperature for 2 weeks in Optisol is superior to preservation in Dexsol. Both media may be useful in preserving endothelial structure for limited periods at room temperature, which could provide a measure of safety in shipping or storage where refrigeration is unreliable.

management of the posterior capsule following posterior chamber lens implantation

A retrospective review of posterior capsule management in 595 consecutive unselected posterior chamber lens implants performed between 10/1/76 and 9/30/79 is presented. The incidence of secondary discission required increased from 0.6%, in cases with zero to six months follow-up, to 18.4%, in cases with 24 to 36 months follow-up, to 18.4%, in cases with 24 to 36 months follow-up. A plano-convex posterior chamber lens design which allows the convex surface of the implant to contact the posterior capsule reduced the incidence of posterior capsule opacification by providing a barrier to cortical cell migration. When secondary discission is needed behind a posterior chamber lens, it may be performed successfully using a pars plana approach. Our data suggest that the incidence of the major complications of this technique, i.e. cystoid macular edema and retinal detachment, may be reduced by delaying capsulotomy for 12 months after implant surgery.

Topical diclofenac in the treatment of ocular pain after excimer photorefractive keratectomy

BACKGROUND Following excimer laser photorefractive keratectomy, patients experience significant ocular pain until corneal reepithelialization. Despite the use of cold compresses, bandage soft contact lenses, cycloplegics, narcotics, and topical corticosteroids, the pain has not been adequately controlled in many patients. METHODS A randomized, double-masked, parallel-group study of diclofenac sodium 0.1% ophthalmic solution and its placebo vehicle was evaluated. Patients undergoing excimer myopic photorefractive keratectomy on their second eye were admitted overnight. Postoperative procedures included two drops of diclofenac or placebo immediately after surgery and then qid until reepithelialization, topical tobramycin (qid), 0.1% fluorometholone (q2h), cycloplegics, and a disposable soft contact lens. Thirty-two patients (diclofenac = 16, placebo = 16) were evaluated from +30 minutes to +96 hours by several types of questionnaires. RESULTS Most patients who received placebo experienced pain, starting within 1 hour, peaking at 4 to 6 hours and lasting 36 to 48 hours. The diclofenac-treated patients rarely experienced the early peak in pain, had less pain overall until 72 hours postoperatively, and experienced significantly less photophobia and burning/stinging. Significantly fewer patients on diclofenac required oral narcotics. Three patients (diclofenac = 2, placebo = 1) developed corneal infiltrates, the etiology of which is not known. In a separate study we conducted, there was no difference in epithelial healing times between the diclofenac-treated eyes and those not receiving the drug. CONCLUSIONS Diclofenac appears to significantly reduce the ocular pain following excimer photorefractive keratectomy.