Lasso procedure to revise overcorrection with radial keratotomy.

PURPOSE: To report three patients who underwent the lasso procedure to revise overcorrection with radial keratotomy. METHODS: Case report and review of the literature. RESULTS: Four eyes of three patients who had undergone radial keratotomy with resultant hyperopic overcorrection underwent a lasso procedure. Before the procedure, average cycloplegic refraction spherical equivalent was +3.656 +/- 1.352 diopters, and average manifest refraction spherical equivalent was +2.250 +/- 0.621 diopters. A 10.0 monofilament nylon suture was placed in a circumferencial manner through the corneal stroma and overlapping the old radial keratotomy incisions. At 1 month postoperatively, best-corrected visual acuity was 20/20 in all four eyes, with average cycloplegic refraction spherical equivalent +0.438 +/- 1.423 diopters and average manifest refraction spherical equivalent -0.156 +/- 1.147 diopters. Mean delta cycloplegic refraction spherical equivalent was 3.219 +/- 1.724. CONCLUSIONS: The lasso procedure provides an immediate solution for symptomatic overcorrected hyperopic eyes after radial keratotomy. Predictability and long-term stability necessitate further follow-up.

Arcuate transverse keratotomy for astigmatism followed by subsequent radial or transverse keratotomy. ARC-T Study Group. Astigmatism Reduction Clinical Trial.

BACKGROUND: We studied the safety and efficacy of arcuate transverse keratotomy performed for the primary correction of naturally occurring corneal astigmatism. METHODS: A multicenter, prospective evaluation of one-stage arcuate transverse keratotomy was conducted in 160 eyes with 1.00 to 6.00 diopters (D) of naturally occurring astigmatism. Vector analysis was used. After 1 month, those eyes that needed further refractive surgery received radial keratotomy for myopia and second-stage arcuate transverse keratotomy for residual astigmatism. RESULTS: Mean preoperative refractive cylinder was 2.80 D. At 1 month, the vector-corrected change was 2.30 D. Eighty-eight (61%) eyes had at least 1.00 D of residual refractive cylinder and 24 (17%) had at least 2.00 D. Eyes undergoing a second surgery averaged 1.60 D of vector-corrected effect, for a total effect of 2.90 D from both surgeries, indicating the astigmatic refractive effects were not additive. Eyes that had radial keratotomy alone as the second surgery demonstrated a similar change in refractive cylinder as eyes that had both radial and transverse keratotomies. Two eyes lost two lines of spectacle-corrected visual acuity, 29 eyes lost one line, 84 showed no change, and 26 eyes improved one line. CONCLUSION: Arcuate transverse keratotomy reduced refractive astigmatism. Both overcorrection and undercorrection were common. Complications were infrequent but occasionally caused significant irregular astigmatism. Arcuate transverse keratotomy appears to be a safe procedure with few complications.

Astigmatism reduction clinical trial: a multicenter prospective evaluation of the predictability of arcuate keratotomy. Evaluation of surgical nomogram predictability. ARC-T Study Group.

OBJECTIVE: To determine the accuracy of the Lindstrom surgical nomogram for astigmatism. DESIGN: A prospective multicenter study. PATIENTS: One hundred sixty eyes of 95 patients underwent astigmatic keratotomy in eight centers by nine surgeons. Inclusion criteria for the study included age of at least 18 years with 1 to 6 diopters (D) of naturally occurring corneal astigmatism and less than 1 D of lenticular astigmatism. INTERVENTIONS: A standardized astigmatic keratotomy surgical technique was performed on each eye. Surgical measurements were determined using the Lindstrom surgical nomogram for astigmatism. MAIN OUTCOME MEASURE: The Holladay, Cravy, Koch vector analysis method was used to determine the change in refractive cylinder results. Refractive changes also are presented without vector analysis merely using the absolute change in refractive cylinder and axis. RESULTS: Multiple regression analysis was used to develop a mathematical model determining the factors predictive of the change in refractive cylinder. The significant predictors for the amount of astigmatic correction achieved were, in order of decreasing importance, the following: number of incisions (R2 = 30%), incision length (R2 = 16%), age (R2 = 8%), and gender (R2 = 2%). CONCLUSIONS: Astigmatism is a two-dimensional measurement of both quantity and direction that is most appropriately analyzed with vector analysis. The original Lindstrom surgical nomogram for arcuate keratotomy used in this study is still quite useful although it tended to underpredict results for many patients, especially those having two incisional surgeries. Some older subjects having minimal surgery achieved greater correction than predicted by the original nomogram. The most important factors predictive of greater astigmatic keratotomy surgical effect are incision number, incision length, older age, and male gender.

Unpreserved carboxymethylcellulose artificial tears evaluated in patients with keratoconjunctivitis sicca.

In order to evaluate the therapeutic value of an unpreserved carboxymethylcellulose-based artificial tear in treatment of keratoconjunctivitis sicca (KCS), 56 patients with severe keratoconjunctivitis sicca were enrolled, at a single study center, in a randomized, double-masked, 8-week comparison with a preserved hydroxypropylmethylcellulose (HMC)-based artificial tear. Patients treated with the carboxymethylcellulose (CMC)-based tear showed significant improvement in fluorescein staining, symptoms, and impression cytology grades. Patients treated with HMC-based tears showed minimal improvement in a few variables. Impression cytology specimens were analyzed by a modified technique that maps the distribution of the various grades present on the specimen. With this technique, improvement in the cytology grades was noted in the group of patients using CMC-based tears. The improvement correlated with observed decreases in symptoms of discomfort and with scores for superficial punctate staining. This study supports the observed therapeutic value of unpreserved CMC-based artificial tears and suggests the possible reversal of squamous metaplasia in patients with KCS. Further studies are required to separate the benefit of the CMC formulation from the benefits of preservative elimination.

Cartography of impression cytology.

Impression cytology is a minimally invasive diagnostic procedure allowing the collection of a monolayer of cells from the conjunctival surface. Both light and electron microscopy study of individual cellular changes, as well as the analysis of two-dimensional ocular surface changes, can be evaluated. Its most widespread application is for the detection and grading of squamous metaplasia. Grades for the morphological changes of squamous metaplasia have been described. We have developed a regional mapping technique that records the distribution of the various grades over the ocular surface areas sampled. This technique may offer greater sensitivity to variations in the distribution of squamous metaplasia in response to disease or therapy.

The anchor suture for securing loosened, continuous sutures in penetrating keratoplasty.

To secure a penetrating keratoplasty donor button, a continuous suture is both less time consuming to place and easier to remove. Infrequently, however, the continuous suture may loosen or break prematurely. For this purpose we propose the anchor suture as a simple technique to restore a tight, continuous suture and a secure wound.

Postoperative management of epikeratoplasty.

Epikeratoplasty is the surface implantation of devitalized human corneal tissue onto a recipient cornea for optical rehabilitation. Its postoperative management can be divided into three stages: (1) epithelialization, (2) suture management, and (3) restoration of visual function. Careful attention to each of the healing phases and the multiple potential complications that commonly arise is required for a satisfactory level of visual performance to be achieved in a high proportion of cases.

Sensitization of bleached Stentor to far UV.

Stentors are more sensitive to far UV-induced delay of oral regeneration following bleaching of their UV-absorbant cortical pigment granules. This finding supports a subcortical location of UV-sensitive sites.