Volume 4, Number 13

Monday, March 29, 2004

In this issue: (click heading to view article)
		Astigmatism Outcomes of Horizontal Temporal vs. Nasal Clear Corneal Incision Cataract Surgery
		Factor XII Deficiency as a Thrombophilic Risk Factor for Retinal Vein Occlusion
		Retinopathy Associated with MI Treated with Percutaneous Coronary Intervention
		Using the 76-Suprathreshold Visual Field Test to Detect VFD by Humphrey Threshold Testing
		Limbal Autograft and Allograft Transplants for Corneal Burns
		Briefly

Astigmatism Outcomes of Horizontal Temporal vs. Nasal Clear Corneal Incision Cataract Surgery In a retrospective study by the Wilmer Eye Institute at Johns Hopkins Hospital, Baltimore, researchers comparing short- and long-term with-the-rule (WTR) astigmatism outcomes after cataract surgery using temporal clear horizontal corneal incisions and nasal horizontal clear corneal incisions found that temporal incisions may induce significantly less astigmatism than nasal incisions. The study included a consecutive series of 178 eyes (94 right, 84 left) of 161 patients having phacoemulsification with implantation of a 6.0 mm foldable acrylic intraocular lens through a 3.5 mm horizontal clear corneal incision at 180 degrees (temporal incision in right eyes, nasal incision in left eyes). Investigators measured astigmatism by keratometry readings before surgery and six weeks and 12 months postoperatively. The mean preoperative astigmatism in the 178 eyes was 0.78D. Against-the-rule (ATR) astigmatism was evident in 54.5 percent of eyes, while 22.5 percent had WTR astigmatism; 14.0 percent were astigmatically neutral. A significant shift toward WTR astigmatism occurred postoperatively: at six weeks, 48.3 percent of eyes had WTR astigmatism and 23.0 percent had ATR astigmatism. At 12 months, 43.8 percent had WTR astigmatism and 25.8 percent had ATR astigmatism. Vector analysis revealed a mean surgically induced astigmatism of 1.17D at six weeks and 1.04D at 12 months. The side of the incision significantly affected surgically induced astigmatism. At six weeks, temporal incisions yielded a mean surgically induced astigmatism of 0.74D and the nasal incisions yielded a mean surgically induced astigmatism of 1.65D. This trend in surgically induced astigmatism persisted at 12 months: 0.71D for temporal incisions and 1.41D for nasal incisions.

SOURCE: Barequet IS, Yu E, Vitale S, et al. Astigmatism outcomes of horizontal temporal versus nasal clear corneal incision cataract surgery. J Cataract Refract Surg 2004;30(2):418-23.

Factor XII Deficiency as a Thrombophilic Risk Factor for Retinal Vein Occlusion Factor XII deficiency is among the coagulation disorders that have been implicated in major thromboembolic events. However, little is known about an association of this coagulation disorder and retinal vessel occlusion (RVO). In this cross-sectional study, German researchers investigated the prevalence of Factor XII deficiency in patients with RVO with reference to age and cardiovascular risk factors and found that the deficiency is highly prevalent in RVO patients 45 years old or younger. By contrast, the prevalence of Factor XII deficiency in RVO patients older than 45 years appears to be similar to that seen in healthy individuals. Investigators prospectively screened 150 consecutive patients with central or branch retinal vein occlusion and 135 subjects matched for age and gender for Factor XII deficiency. Both groups were divided into two subgroups, depending on patient age at the time of the RVO or a previous thromboembolic event: Group 1 consisted of patients 45 years old or younger; Group 2 consisted of patients older than 45. Overall, Factor XII deficiency was present in 14 (9.3 percent) of 150 patients and in one (0.7 percent) of 135 controls. Patient age in Group 1 was associated with a high prevalence of Factor XII deficiency (18 percent). By contrast, only 5 (5 percent) of 100 patients in Group 2 and none of the young controls tested positive for Factor XII deficiency. The prevalence among patients in Group 1 was similar to that found in age-matched controls (2 percent).

SOURCE: Kuhli C, Scharrer I, Koch F, et al. Factor XII deficiency: a thrombophilic risk factor for retinal vein occlusion. Am J Ophthalmol 2004;137(3):459-64.

Retinopathy Associated with MI Treated with Percutaneous Coronary Intervention Investigators at the Jichi Medical School, Saitama, Japan, believe they have identified a new form of retinopathy in patients with acute myocardial infarction (AMI) that spontaneously subsides without treatment. Serial ophthalmological examinations were conducted in 40 patients who underwent percutaneous coronary intervention (PCI) following AMI. Thirty of these patients were diagnosed with AMI; the other 10 had stable angina pectoris. Cotton wool spots developed in 17 patients (57 percent) from the group with AMI undergoing PCI within two months. Of these, seven patients (41 percent) also developed superficial hemorrhages. Retinopathy was most prominent one to two months after AMI and then tended to become quiescent afterwards, without treatment.

SOURCE: Kinoshita N, Kakehashi A, Yasu T, et al. A new form of retinopathy associated with myocardial infarction treated with percutaneous coronary intervention. Br J Ophthalmol 2004;88(4):494-6.

Using the 76-Suprathreshold Visual Field Test to Detect VFD by Humphrey Threshold Testing The 76-Suprathreshold (76-STHR) visual field test to detect eyes with visual field defect (VFD) shows high sensitivity and low false-negative results at the at-least-one-point-missed cutoff level criterion used to detect eyes with VFD by Humphrey threshold testing, according to researchers in Greece. Eighty-eight subjects who agreed to participate in the pilot phase of the Thessaloniki Eye Study underwent a 76-STHR visual field test followed by a 30-full threshold (30-2 FTHR) test (Humphrey field analyzer). One eye/subject was randomly selected and included in the analysis. Researchers calculated sensitivity and specificity rates of the 76-STHR to detect eyes with VFD by the 30-2 FTHR test. When eyes with borderline results in the 30-2 FTHR test were classified as having a VFD, sensitivity rates of the 76-STHR to detect eyes with VFD by the 30-2 FTHR were 85.2 percent, 77.8 percent, and 74.1 percent, whereas specificity rates were 70 percent, 78 percent, and 86 percent, depending on the cutoff used for the 76-STHR. The authors conclude that the 76-STHR criterion should be used when screening in a population-based study setting, although it would not be the appropriate screening test in a primary care setting with limited resources.

SOURCE: Topouzis F, Coleman AL, Yu F, et al. Sensitivity and specificity of the 76-Suprathreshold visual field test to detect eyes with visual field defect by Humphrey threshold testing in a population-based setting: the Thessaloniki eye study. Amer J Ophthalmol 2004;137(3):420-5.

Limbal Autograft and Allograft Transplants for Corneal Burns Limbal autograft transplantation is an effective and safe procedure for unilateral corneal burns, while limbal allograft transplantation may be better combined with penetrating keratoplasty for a better visual outcome and higher graft survival rate, according to a study by Turkey's Ankara University School of Medicine. The study included 20 patients (22 eyes) with chemical burn and two patients (two eyes) with thermal burn. Surgeons performed limbal autograft or limbal allograft transplantation in all patients, and in limbal allografting all procedures used donor tissue from live relatives. HLA-typing was tested before allograft surgeries. The patients received systemic cyclosporine A for immunosuppression. Results showed that the corneal surface was successfully reconstructed in all eyes after limbal autografting. Two eyes required additional amniotic membrane transplantation and one eye required allografting. The mean follow-up period for limbal autografts was 13.9 +/- 7.0 months. Limbal allografting failed to reduce corneal vascularity and opacification in five eyes (55.6 percent) and was successful only in four eyes (44.4 percent; mean follow-up 16.2 +/- 11.2 months). In all, 15 eyes undergoing limbal autografting completed re-epithelialization of the cornea at a mean of 35.6 +/- 60.2 days. The mean epithelial healing time in nine eyes undergoing limbal allografting was 13.0 +/- 7.3 days. After limbal autografting, functional vision (>/=1/10) was attained in 12 eyes (80 percent). Only one eye (11.1 percent) achieved functional vision after limbal allografting. Penetrating keratoplasty was performed in three patients following limbal allografting. No cyclosporine-associated side effects were observed. The study's authors state that systemic immunosuppression seems to be necessary for limbal allografts even in the presence of HLA-matched donor tissues.

SOURCE: Ozdemir O, Tekeli O, Ornek K, Arslanpence A, Yalciotandag NF. Limbal autograft and allograft transplantations in patients with corneal burns. Eye 2004;18(3):241-8.

BRIEFLY FDA APPROVES VIEWPOINT CK SYSTEM FOR TREATING PRESBYOPIA. Refractec, Inc., has received FDA approval for its ViewPoint CK System for performing the NearVision CK (Conductive Keratoplasty) procedure to treat presbyopia. A minimally invasive procedure, NearVision CK uses radio waves to shrink small areas of collagen, creating a constrictive band that increases corneal curvature and brings near vision back into focus. It can be performed in less than three minutes in a doctor’s office with eye-drop anesthesia, and no tissue is cut or removed. The FDA approved the CK procedure for age-related hyperopia in 2002; with the current approval, NearVision CK will be indicated for the temporary improvement of near vision in emmetropic and hyperopic presbyopes. The procedure is typically performed on just one eye to avoid compromising the patient’s binocular distance vision. The FDA based its new approval on clinical trial data collected at the 12-month follow-up visit in which NearVision CK demonstrated effectiveness in significantly improving patients’ near vision: 98 percent could see J5 (magazine- and newspaper-size print) in the treated eye; 87 percent could see 20/20 in the distance and also read J3 (phone book-sized print). No serious, sight-threatening or unanticipated safety events were reported. LUMENIS MAY END AGREEMENT WITH WAVELIGHT LASER. WaveLight Laser Technologies AG of Germany recently sent a notice of termination of a distribution agreement with Lumenis, Ltd. The agreement covers Europe and other areas outside the United States, where Lumenis markets and sells WaveLight Laser products, including the Allegretto Wave excimer laser. Lumenis had hoped to renegotiate the distribution agreements with WaveLight, which did not meet the company's profit objective; however, with the receipt of the notice of termination, Lumenis says it will re-evaluate its position. Lumenis and WaveLight intend to discuss the future of the U.S. sales representative agreement between the parties and their continued cooperation in that market; under that agreement, Lumenis is the exclusive WaveLight sales agent, responsible for marketing, sales and service and support. PHASE III TRIALS FOR NSAID TO TREAT OCULAR INFLAMMATION SHOW PROMISING RESULTS. ISTA Pharmaceuticals, Inc., recently announced positive results from the company's Phase III clinical trials of Xibrom, a topical, twice-daily, non-steroidal anti-inflammatory solution. Xibrom is initially being developed to treat ocular inflammation after cataract surgery. ISTA intends to file a New Drug Application for Xibrom with the FDA in the second quarter of 2004, based on trial results thus far.

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