Laser in situ keratomileusis to correct residual myopia and astigmatism after radial keratotomy.

PURPOSE: To evaluate the safety and efficacy of laser in situ keratomileusis (LASIK) in selected post-radial-keratotomy (RK) eyes with residual myopia and astigmatism. SETTING: TLC-The Brea Laser Eye Center, Brea, California, USA. METHODS: Nine eyes of 6 patients who had had RK but had residual myopia and/or astigmatism had LASIK. All RK eyes had 8 radial incisions, were more than 1 year post-RK, had no epithelial inclusion cysts or corneal disease, and had had no subsequent ocular surgery. Follow-up was a minimum of 13 months, at which time uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), manifest refraction, cycloplegic refraction, keratometry, central and peripheral pachymetries, intraocular pressure, and a subjective assessment of visual function were obtained. RESULTS: At the last follow-up, the mean spherical equivalent (SE) was -0.156 diopter (D) +/- 0.174 (SD). All eyes treated for distance vision had a UCVA of 20/25 or better. No patient lost BCVA. No intraoperative or postoperative complications occurred. Seven eyes had morning and evening measurements. The mean change in manifest SE from morning to evening was -0.143 D. Six of the 7 eyes (86%) had 0 to 1 Snellen line change in UCVA from morning to evening. The subjective questionnaire revealed a high degree of satisfaction with overall vision, minimal glare, and less fluctuation in daily vision than before LASIK. CONCLUSION: Laser in situ keratomileusis is safe and efficacious for reducing residual myopia and astigmatism in properly selected RK patients.

Topical intrastromal steroid during laser in situ keratomileusis to retard interface keratitis.

PURPOSE: To evaluate the effect of an intraoperative topical intrastromal steroid on the incidence and severity of nonspecific diffuse intralamellar keratitis (NSDIK). SETTING: T.L.C. The Laser Center, Brea, California, USA. METHODS: This prospective study included 2 cohort groups, each consisting of 105 consecutive eyes treated with laser in situ keratomileusis (LASIK) for myopia and astigmatism. Group A received the standard LASIK medication protocol and Group B, an additional drop of prednisolone sodium phosphate 1% solution on the undersurface of the cap immediately after it was reflected, prior to initiating the laser treatment. After the laser treatment was completed, the flap was repositioned; 1 minute after the steroid application, the interface was irrigated. All patients were examined postoperatively and placed in 1 of 4 categories: no interface keratitis, grade 1 (mild), grade 2 (moderate with decreased vision), or grade 3 (severe with decreased vision). RESULTS: The incidence of NSDIK in Group A was 17.1% (18 eyes); 14 eyes (78.0%) were grade 1 and 4 (22.0%), grade 2. The incidence in Group B was 6.7% (7 eyes); all eyes were grade 1. Topical intrastromal steroid application significantly reduced the incidence and severity of NSDIK (P < .01). CONCLUSION: We propose that intraoperative intrastromal steroid application is a safe and effective way to reduce the incidence and severity of NSDIK.

Intraoperative succinylcholine and the postoperative eye alignment.

In 99 patients undergoing strabismus surgery, an intravenous bolus of succinylcholine (Sch) was given after completion of the strabismus procedure. Reliable data were obtained in 53 patients. The interlimbal distance measured at 60 seconds after injection (VR60) was compared to the interlimbal distance at 1 and 6 weeks postoperatively, to evaluate the correlation between the drug-induced eye position under anesthesia and the awake-eye alignment postoperatively. Correlations were highest in patients undergoing symmetric recessions of the medial or lateral recti in primary horizontal strabismus. Confidence intervals of 0.8 to 1.2 were noted for both the esotropia and exotropia groups. Two patients experienced Sch-related complications of masseter spasm and prolonged apnea. Although infrequent, the potential gravity of the complications from Sch use and the currently enjoyed high rate of success in primary strabismus surgery suggest that these formulas not be used clinically. Nonetheless, the high correlations between the drug-induced and awake ocular position provide further support to the premise that the Sch sensitive fibers provide an important motor component to the awake eye position.

Synergistic divergence: saccadic velocity analysis and surgical results.

The clinical findings are described in four patients with synergistic divergence (SD), an ocular motility disorder which is considered to be a variant of Duane retraction syndrome (DRS). Saccadic velocity studies in three patients demonstrated preserved abducting saccades in the affected eye with equally reduced amplitudes on both attempted abduction and adduction. The preserved saccades on attempted abduction of the affected eye, coupled with electromyographic evidence that shows maintenance of normal reciprocal innervation with respect to gaze on attempted abduction as dictated by Sherrington's law, strongly suggest that the abducens nerve is not necessarily absent or severely hypoplastic in this condition. One patient showed typical DRS in the contralateral eye and had a son with bilateral DRS, attesting to a possible genetic and etiologic relationship between SD and DRS. Three patients underwent strabismus surgery. Review of our surgical results and an analysis of the literature indicate that a crippling procedure to the ipsilateral lateral rectus muscle, such as extirpation, may be necessary to eliminate simultaneous abduction. Overcorrection did not occur following lateral rectus extirpation.

Succinylcholine-stimulated muscle tensions following botulinum injection in the domestic cat.

Succinylcholine (SCh) selectively stimulates, and can therefore selectively assay, the multiple innervated (MI) fiber system of the extraocular muscles. Since botulinum-A toxin has been observed to induce changes in eye position in humans, SCh was used to assess the effect of botulinum-A on the SCh-sensitive MI fibers of extraocular muscles. Intravenous SCh infusion (40 micrograms-1 kg-1 min-1 was performed in the anesthetized domestic cat. Thirty-eight infusions were performed in 19 normal controls, measuring the peak tensions generated in the four horizontal and four vertical rectus muscles. Succinylcholine-stimulated muscle tensions (SSMT) were then repeated in nine animals, 4 weeks and 10 weeks following injection of botulinum-A toxin into both medial rectus muscles. Mean peak SSMTs were unchanged at 4 and 10 weeks following botulinum injection when compared to controls. We propose that botulinum chemo-denervation has no acute or chronic effect on the MI SCh-sensitive muscle fibers of the medial recti of the domestic cat. This lack of effect on the postsynaptic MI fibers indirectly supports light and electron microscopic studies which show changes predominantly in the singly innervated (SI), rather than the MI fibers following botulinum injection. Mean peak SSMTs were also greater for medial and superior rectus muscles compared to lateral and inferior recti respectively, suggesting a greater number or proportion of MI fibers in medial and superior recti.

Synergistic divergence and jaw-winking phenomenon.

Synergistic divergence is a congenital syndrome of monocular adduction deficit, with simultaneous abduction of both eyes on attempted gaze into the field of action of the paretic medial rectus muscle. Based on electromyographic data, it has been speculated that it is a neural miswiring disorder related to Duane's retraction syndrome. The association between Duane's retraction syndrome and the Marcus Gunn jaw-winking phenomenon, another neural miswiring disorder, has been previously reported. The authors describe a patient with both bilateral synergistic divergence and Marcus Gunn jaw-winking phenomenon.

Thyroid eye disease presenting after cataract surgery.

Strabismus presenting after cataract surgery has been attributed to a variety of disorders, some of which are unrelated to the surgery. When thorough ophthalmologic and neurologic examinations fail to elucidate a definitive etiology, the motility disturbance is often ascribed to operative trauma to the orbital soft tissues. In a series of 58 patients with strabismus presenting after cataract surgery, eight (14%) were found to have previously unsuspected thyroid eye disease. Three of the eight patients had past histories of systemic dysthyroidism, but none reported diplopia prior to cataract extraction. Three of the remaining five patients showed normal thyroid function tests. Absence of diplopia prior to cataract extraction in these patients may be due to: 1) poor vision precluding diplopia until surgical restoration of sight; 2) intraoperative aggravation of the inflammatory process in otherwise subclinical thyroid eye disease; or 3) onset of clinical thyroid eye disease that was temporally associated with cataract surgery by chance. Thyroid eye disease should be included in the differential diagnosis of all patients presenting with binocular diplopia following cataract surgery. Suitable neuroimaging studies may be needed to confirm the diagnosis.

A caliper-hook for strabismus surgery.

An instrument to assist in resection surgery consists of a telescoping hook within a second hook that can be spread a calibrated distance. Its primary purpose is to maintain a constant tension and an accurate measure of tendon length during suture passage. Additionally, the grooved distal hook supports the needle and protects the globe from needle trauma.

A comparison of the succinylcholine induced ocular position and the postoperative alignment in strabismus.

Succinylcholine was injected intraoperatively in 41 strabismus patients with congenital esotropia or intermittent or constant exotropia. Regression analyses were performed to investigate the predictive relationships between the one-, six-, and 26-week postoperative alignment and the intraoperative, succinylcholine-induced ocular position. Ocular position, determined by the interlimbal distance in millimeters, was calculated using a semi-automated, video replay analysis system. Large, statistically significant correlation coefficients were obtained for patients undergoing bimedial recessions of 4.0 to 5.5 mm and bilateral lateral rectus recessions of 5.0 to 7.0 mm. Small correlations were obtained for esotropes undergoing the recession/resection procedure and those with bimedial recessions of 6.0 mm or greater. These data support the theory that the succinylcholine-sensitive subgroup of the extraocular muscle fibers are those whose tonic contracture provide the motor component to ocular alignment. Sample sizes at present are insufficient to suggest clinical use of these data. In future research, these relationships will be tested for their ability to predict postoperative alignment and thereby, improve success rates in strabismus surgery.

Reliability and variability in the measurement of interlimbal distance with a semiautomated video replay analysis system (SAVRAS).

This paper reports on the reliability and variability of a semi-automated, video replay and analysis system (SAVRAS) in determining interlimbal distance in patients with strabismus. Factors under investigation were: choice of observer, choice of video frame, patient age and patient state (awake or anesthetized). It was demonstrated that SAVRAS was a highly reliable and reproducible system. This system is currently in use to evaluate the relationship between the succinylcholine induced ocular position, under anesthesia, and the postoperative awake alignment.

Sequelae of botulinum toxin injection.

A total of 136 injections was given to 83 patients for strabismus (99 injections), blepharospasm (29 injections), and spastic entropion (eight injections). All four patients with entropion experienced temporary benefits and early recurrence; one injection resulted in temporary paralytic ectropion. Two of 13 patients treated for blepharospasm developed transient bilateral blepharoptosis. Temporary and related sequelae of extraocular muscle injection included one periocular hemorrhage, one total ophthalmoplegia, and a 44% incidence (29 of 66 patients) of blepharoptosis, which in two patients lasted more than six months. Within three days of injection one patient developed homolateral acute herpes simplex keratitis and a second died of an acute myocardial infarction. No causal relationship for these events has been established.

Succinylcholine as a predictor in strabismus surgery.

Succinylcholine was injected intraoperatively in 20 patients with congenital esotropia, before and after the surgical procedure. Regression analysis was performed to investigate the relationship between the awake pre- and postoperative alignment and the drug-induced ocular positions, under anesthesia. The postoperative succinylcholine-induced ocular position was found to be a highly significant predictor of the one week postoperative alignment (r = 0.98, p less than 0.0001). Further investigation may lead to an ability to predict the postoperative alignment intraoperatively.

Gene for hereditary retinoblastoma assigned to human chromosome 13 by linkage to esterase D.

Evaluation of three families with hereditary retinoblastoma demonstrates close linkage of the gene for this tumor with the genetic locus for esterase D. These results assign the gene for the hereditary form of retinoblastoma to band q14 on chromosome 13, the same region which is affected in the chromosome deletion form of this eye tumor, and therefore suggest a common underlying mechanism in the pathogenesis of these two forms of retinoblastoma.

Abberrant muscular insertions in Crouzon's disease.

Herein we present a case of Crouzon's disease with anomalous medial rectus formation and horizontal recti insertions. This adds a feature of the disease to the literature and reminds us to approach strabismus in orbital anomalies cautiously via a limbal peritomy. As the overall prognosis for these patients continues to improve we anticipate that more of these patients will seek strabismus surgery.