Position-induced Cyclotorsion under Monocular Fixation

PURPOSE: To determine whether cyclotorsion occurs when a patient moves from the seating to supine position fixating with one eye. METHODS: The axis of astigmatism was measured with the handheld automated refractometer (Retinomax K-plus, Nikon, Japan) in 33 eyes having more than -1.0D cylinder in seated and supine positions under monocular fixation. RESULTS: There was a cyclotorsional deviation in 30 eyes (90.90%). Excyclotorsion was shown in 22 eyes (66.67%) and incyclotorsion in 8 (24.24%). Seventeen eyes (51.50%) had a torsional deviation less than 4 degrees, 5 eyes (15.15%) from 5 to 6 degrees, 7 eyes (21.21%) from 7 to 14 degrees and one eye greater than 15 degrees. CONCLUSIONS: Positionally induced cyclotorsion occurs under fixation with one eye simulating refractive surgery. Surgeons should therefore make an effort to align the wavefront measurement to the ablation onto the cornea.

Pachymetric Measurements Using Orbscan after Excimer Refractive Surgery

PURPOSE: To assess the accuracy of pachymetric measurement using Orbscan(Bausch and Lomb, USA) after laser in situ keratomileusis(LASIK), photorefractive keratectomy(PRK), and laser epithelial keratomileusis (LASEK). METHODS: Central corneal thickness of 159 nonoperated normal eyes, 55 eyes after LASIK, 12 after PRK, and 17 after LASEK was measured using ultrasound and Orbscan II. The acoustic factor (AF) was adjusted, based on the results obtained in the normal eye group, to minimize the difference between ultrasound and Orbscan pachymetric values. RESULTS: Using the adjusted AF (0.9607), the mean difference between Ultrasonic pachymetric and Orbscan measurement was 0.00 +/- 21.08, 20.44 +/- 24.12, 27.63 +/- 36.87, and 0.56 +/- 17.26 micro meter in the normal, LASIK, PRK, and LASEK groups, respectively. In the LASIK and PRK groups, there was a statistically significant difference between the two methods (both P<0.001). The postoperative ultrasound measurements were consistent with the theoretical residual corneal thickness in the LASIK and PRK groups (-2.96 +/- 18.00 micro meter, -1.00 +/- 13.59 micro meter), while Orbscan measurements were statistically significantly less than the theoretical residual corneal thickness in the LASIK and PRK groups (21.84 +/- 31.06 micro meter, p<0.001; 21.88 +/- 35.91 micro meter, P=0.036). CONCLUSIONS: Orbscan pachymetric values may be underestimated and less accurate after excimer refractive surgery, especially after LASIK and PRK.

Long-term Clinical Result and Patient Satisfaction after LASIK

PURPOSE: To evaluate the long-term clinical result and patient satisfaction after laser in situ keratomileusis. METHODS: This is a long term (over 3 years) retrospective analysis of 107 eyes (54 patients) that has undergone LASIK since February 1996. RESULTS: Mean preoperative Spherical Equivalent(SE) was -7.81 +/- 4.07D and mean postoperative SE was -0.88 +/- 1.74D at 1 week, -1.18 +/- 1.17D at 1 month, -1.32 +/- 1.71D at 3 month and -2.44 +/- 2.20D after 3 years. At the last visit, uncorrective visual acuity was 0.5 or better in 83.1% and 26.2% of manifest SE was within the +/- 1D. However, in high myopic group (>-10.D), it has decreased to 41.7% and 0% respectively. Myopic progression occurred also in reoperation cases, 81.3% had uncorrective visual acuity of 0.5 or better and 31.3% had manifest SE within +/- 1D at the last visit. In the survey of subjective satisfaction, 80.2% of patient was satisfied with the surgery, which has decreased to 46.2% after long term follow-up. CONCLUSIONS: In conclusion, the higher the preoperative SE, the more myopic regression has occurred (p0.05). The patient subjective satisfaction has significantly decreased after long term follow-up compared to immediate postoperative visit.

Superficial Punctate Keratopathy after LASIK

PURPOSE: To evaluate the clinical characteristics of superficial punctate keratopathy following LASIK and to estabilish the management and prevention of superficial punctate keratopathy. METHODS: We retrospectively analyzed the medical records of 476 eyes followed up for more than 6 months after LASIK. RESULTS: Of the 476 eyes, the SPK has deveolped in 118 eyes (24.8%). The incidence was higher when there was a history of dry eye symptoms or contact lens intolerance (p<0.05%). In 68 eyes (57.6%), SPK has developed within 1 month after LASIK and the inferior cornea (85.6%) was the most frequently involved site. Most cases were asymptomatic and treated with preservative-free artificial tear solution. There were no visually significant complications. CONCLUSIONS: Corneal sensitivity decreases after LASIK by cutoff of the sensory innervation. As LASIK-induced neurotrophic epitheliopathy has an influence on tear film dynamics, it may be a possible cause of dry eye syndrome or epithelial keratopathy after LASIK. Careful attention should be taken into the contributing factors such as pre-existing dry eye syndrome, contact lens intolerance, previous history of blepharoplasty, lagopthalmos and so on. Adequate hydration of cornea preoperatively, careful manipulation during procedure, conservative treatment with artificial tears may be helpful in reducing symptoms and preventing further complications.

Screening Examination for Retinopathy of Prematurity with Dual Parameter Protocol

So far most screening protocols for retinopathy of prematurity (ROP)have used a single parameter such as chronological age or postconceptional age. We attempted to test a screening protocol for ROP using dual parameter, chronological age and postconceptional age, to determine whether it could reduce the number of screening examinations safely.We retrospectively reviewed medical records of 23 infants (43 eyes)who had undergone laser treatment for threshold ROP.Mean gestational age at birth was 28 weeks and mean birth weight was 1055 gms.The mean age at which the study infants reached threshold ROP was 10 weeks in chronological age and 38 weeks in postconceptional age.Screening examinations as early as chronological age of 7 weeks or postconceptional age of 35 weeks could detect all threshold ROP while reducing the number of unnecessary early examinations.

Silicone Intubation for Functional Nasolacrimal Duct Obstruction

Functional nasolacrimal duct obstruction refers to a situation in which the lacrimal system is patent to syringing in a patient complaining of tearing. From July 1995 to July 1998 we performed silicone tube intubation in 29 eyes of 22 patients with functional obstruction of the lacrimal drainage passages. Seventy-two percent of patients had resistance in the lacrimal passage atprobing and proximal nasolacrimal duct was the most frequent obstruction site.Epiphora has improved in 58.6% (17 eyes)after silicone intubation without any improvement in the remaining.Some even became aggravated. Most patients with functional obstruction had partial obstruction in the lacrimal passage and more than half of them became improved with the sil-So silicone intubation can be considered as an initial procedure prior to dacryocystorhinostomy

The Clinical Characteristics of Intermittent Exotropia and Their Relationship

Intermittent exotropia occurs commonly in Korea and its clinical characteristics are relatively well known. We analyzed the clinical characteristics of intermittent exotropia and studied the relationship among them. We examined 229 patients(92 males and 137 females( who first visited three strabismic clinics. The age of onset, frequency, family history and symptoms of intermittent exotropia were examined. The angle and type of deviation were studied and sensory tests were done. The mean age of onset was 32.4 months and frequency ws 39.1% and family history was 8.7%. Photophobia was the most common symptom of intermittent exotropia. The distant angle of deviation was 26.7 prism diopters in average and the near angle was 25.3 prism diopters in average. The most common type of intermittent exotropia was basic type. followed by simulated divergence excess type, convergence insufficiency type, and divergence excess type. In statistical study, there was no significant relationship among clinical characteristics of intermittent exotroia.