James V. Aquavella

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.

Pseudophakic Bullous Keratopathy: Relationship to Preoperative Corneal Endothelial Status

Pseudophakic bullous keratopathy is one of the complications of intraocular lens implantation. A knowledge of the preoperative status of corneal endothelium may help to minimize the incidence of this complication. The preoperative corneal endothelial status of 118 eyes of 102 patients who received Worst-Medallion intraocular lenses more than five years ago was analyzed retrospectively. This data was then correlated with the postoperative clinical status of the cornea. Twelve eyes (10%) underwent penetrating keratoplasty for irreversible corneal edema, and 28 of the remaining eyes (22%) had clinical evidence of peripheral corneal edema. No correlation was found between the preoperative endothelial cell density or the degree of postoperative cell loss and the development of corneal edema. Significant correlation was found between variation in cell size (pleomorphism) and the development of postoperative corneal edema. Greater density of precipitates on endothelium and abnormality in cell shape postoperatively were also frequently seen in corneas that developed edema subsequently.

Community Care of Corneal Ulcers

Because of increasing concern about the appropriate and cost-effective use of eye care services and procedures, several organizations have sought to arrive at practice guidelines or practice patterns from which physicians can draw guidance. To assess the potential effectiveness of such guidelines, we reviewed the care of patients with corneal ulcers. Corneal specialists recommend that cultures be obtained before initiation of treatment. We determined whether ophthalmologists implemented these guidelines by the following: (1) a review of records of 79 patients referred to a tertiary care corneal and external disease service for evaluation of keratitis, and (2) a survey by mail of practicing ophthalmologists. Antibiotic therapy without any cultures was observed in 38 of 79 referred patients with corneal ulcers (48.1%). Our survey of general ophthalmologists disclosed that 274 of 560 patients with corneal ulcers (48.7%) were treated with antibiotics without any cultures being obtained. Compliance with recommended practice in the care of corneal ulcers is poor, as measured with either method. This procedure provides insights into more effective implementation of future practice guidelines.

Correlations Among Upper and Lower Tear Menisci, Noninvasive Tear Break-up Time, and the Schirmer Test

PURPOSE To determine the relationships among tear meniscus parameters, noninvasive tear break-up time (NITBUT), and the Schirmer test. DESIGN Experimental study. METHODS Thirty-six subjects were tested on one randomly selected eye. Real-time corneal optical coherence tomography (OCT) was used to image the upper and lower tear menisci during normal and delayed blinking followed by measurement of NITBUT and the Schirmer test. Digital images of the eye were taken for measuring the lid lengths to estimate tear volume in the menisci. RESULTS Compared with normal blinking, significant increases of tear menisci occurred during delayed blinking (post hoc, P < .01). NITBUT was weakly but significantly correlated with the height (r = 0.36; P = .03) and area (r = 0.37; P = .03) of the lower tear meniscus during normal blinks. NITBUT was also correlated with the lower tear meniscus volume (r = 0.45; P < .05) and total tear meniscus volume (r = 0.43; P < .05) during normal blinking. The Schirmer test was not significantly related to any parameters of the tear menisci, volumes, or NITBUT; however, it was negatively correlated with the age of the subjects (r = -0.47; P = .004). The age was negatively correlated with the upper tear meniscus (r ranged from 0.36 to 0.37 for the radius, height, and area, P < .05) measured during delayed blinking. CONCLUSIONS NITBUT appears correlated with the lower tear meniscus during normal blinking, and the Schirmer test appears not correlated with the noninvasively measured tear meniscus.

Long-Term Changes in Corneal Endothelium Following Intraocular Lens Implantation

To understand the long-term effects of intraocular lens implantation on corneal endothelium, 52 eyes with intraocular lens implantations and 35 eyes with simple cataract extractions were studied using clinical specular microscopy. Endothelial photographs were obtained preoperatively and at least four times in the postoperative period in each case. The postoperative period ranged from 16 to 43 months. Our observations demonstrated that intraocular implants produce a greater magnitude of endothelial cell damage and iris-supported lenses have a more deleterious effect on the corneal endothelium compared with anterior chamber lenses. Seventy-one percent of the eyes with intraocular implants demonstrated precipitates on the endothelium with 16% developing guttata-like areas. All these changes were progressive with time with no such phenomenon occurring in eyes with simple cataract extractions. The progressive endothelial cell damage may be a sequel of chronic, smoldering uveitis associated with intraocular implants.

The Functional Reserve of Corneal Endothelium

With recent advances in our knowledge of corneal physiology, coupled with the development and increasing availability of the specular microscope as a clinical instrument, valid observations relating the morphologic appearance of the corneal endothelium to its functional capacity are within our reach. Manual methods of data analysis are cumbersome, time consuming, and associated with human error and investigator bias. The Omnicon pattern analysis system lends itself to objective analysis of morphologic features, offers the possibility of quantifying the data obtained and, hopefully, will lead to a better understanding of the many aspects of endothelial cell morphology which, in total, relate to the functional reserve of a given cornea.

The Nationwide Study of Epikeratophakia for Aphakia in Children

In the nationwide study of epikeratophakia, 97 surgeons performed a total of 335 procedures in 314 eyes for the correction of aphakia in children under the age of 8 years 1 month. Fifteen children underwent bilateral surgery. Thirty-six tissue lenses were removed and 21 of these eyes underwent a second epikeratophakia procedure. Overall, the success rate for procedures was 89%, and with repeated surgery it was 95% for eyes. Seventy-three percent of the patients were within 3 diopters of emmetropia after surgery. Visual acuity results in patients able to provide verbal responses to the illiterate E, Allen card, or Snellen line chart testing showed improvement in most cases. The safety of epikeratophakia makes it a desirable option for the correction of aphakia in children who are spectacle or contact-lens intolerant, and the permanence of the correction eliminates the problem of optical noncompliance.

The Nationwide Study of Epikeratophakia for Aphakia in Adults

In the nationwide study of epikeratophakia, 154 ophthalmic surgeons who had attended a training course performed 519 procedures for the correction of aphakia in adults: 310 of the eyes had 30 or more days of follow-up after suture removal. Of 229 eyes, 172 (75%) were within 3 diopters of emmetropia after surgery. Of 259 eyes, 245 (95%) demonstrated improved uncorrected visual acuity; 138 (53%) improved by four or more Snellen lines. Of 265 eyes, 209 (78%) achieved within two lines or improved their best corrected visual acuity. Of the 119 patients who achieved or improved their preoperative best corrected visual acuity, 110 (92%) were within two Snellen lines or better by 30 to 60 days after suture removal. Of the 127 patients with more than three months of follow-up after suture removal, 124 (98%) of those between 18 and 70 years of age but only 13 of 23 (54%) of those between 81 and 87 years of age achieved within two lines or better of their best corrected visual acuity. Corneal astigmatism measured by keratometry changed from a preoperative mean (+/- S.D.) of 2.1 +/- 1.8 diopters to a postoperative mean of 2.7 +/- 2.6 diopters. Of the 519 tissue lenses, 22 (4%) were removed, and one third of these patients underwent a second, successful epikeratophakia procedure.

Long-term outcomes of Boston type 1 keratoprosthesis implantation: A retrospective multicenter cohort

PURPOSE To study the long-term outcomes of Boston type 1 keratoprosthesis (KPro) surgery. DESIGN Retrospective, multicenter case series. PARTICIPANTS A total of 158 eyes of 150 patients underwent KPro implantation at 5 participating tertiary centers in the United States between January 2003 and December 2006. Of those, 139 eyes of 133 patients were included in the analyses. METHODS The medical records of consecutive adult patients who received KPro surgery were reviewed. All patients with at least 1 postoperative visit were retained in the outcomes analyses. In eyes in which a repeat KPro procedure was performed, only the outcomes of the initial surgery were analyzed. MAIN OUTCOME MEASURES Visual acuity (VA) outcomes, postoperative complications, and device retention. RESULTS The mean follow-up was 46.7 ± 26 months with all but 4 eyes having at least 6 months of follow-up. Preoperatively, only 10.8% of the eyes had VA of ≥ 20/200. Postoperatively, the VA in 70% of eyes improved to ≥ 20/200. The probability of maintaining VA of ≥ 20/200 at 7 years was 50%. The device retention rate was estimated at 67% at 7 years. The 7-year cumulative incidence of complications was 49.7% for retroprosthetic membrane formation, 21.6% for glaucoma surgery, 18.6% for retinal detachment, and 15.5% for endophthalmitis. CONCLUSIONS Although the risk for complications with longer follow-up seemed to increase, this large multicenter cohort demonstrates favorable outcomes with KPro, with a large number of patients achieving and retaining useful vision over a 7-year period.

Introduction to the use of the Boston keratoprosthesis

The Boston keratoprosthesis (KPro) is one of several types of artificial cornea manufactured worldwide that are being implanted in increasing numbers in patients with severe corneal diseases and graft failures. The prognosis for long-term success varies greatly between diseases, with autoimmune conditions, such as ocular cicatricial pemphigoid and Stevens–Johnson syndrome, and severe chemical burns remaining difficult. In the potentially much larger cohort with little preoperative inflammation, retention is excellent, complications are manageable and outcome is usually very good. Early implantation in congenital corneal opacities to offset amblyopia shows promise. The Boston KPro uses a ‘collar button’ design of polymethyl methacrylate that is sturdy and easily machined and polished, giving excellent vision if the remainder of the eye is healthy. This is implanted into a carrier corneal graft or into the patient’s own cornea. Holes in the back plate allow nutrition from the aqueous humor to reach the graft and long-term use of around-the-clock soft contact lenses protects the ocular surface from excessive dehydration. In nonautoimmune diseases, these measures have virtually eliminated necrosis and melt of the corneal tissue holding the device. Postoperative prophylactic antibiotics can now fully protect eyes from infection.