Myopia Progression of Full Correction and Undercorrection with Myopic Anisometropia

PURPOSE: To investigate the change of refractive error between the full-correction and under-correction treatment groups of myopic anisometropic patients. METHODS: This study included 36 patients who had no amblyopia with myopic anisometropia > 3.00 diopters (D) and less than 6.00 D using the cycloplegic refraction test. The patients were divided into two groups involving the full-correction of both eyes (group 1) or full-correction on the less myopic eye and under-correction with −0.50 D of the more myopic eye (group 2). We monitored refractive changes every 6 months for 24 months. RESULTS: At the first visit, the mean refractive error of the less myopic eye was −0.68 ± 0.54 D and that of the more myopic eye was −4.22 ± 0.77 D in group 1. The mean refractive error of the less myopic eye was −0.75 ± 0.58 D and that of the more myopic eye was −4.36 ± 0.73 D in group 2. There was no significant difference between the groups (p = 0.713 and p = 0.585, respectively). At 24 months, the mean refractive errors of group 1 were −1.27 ± 0.54 D and −4.88 ± 0.81 D, respectively, and that of group 2 were 1.38 ± 0.54 D and −5.59 ± 1.01 D, respectively. The mean refractive error of the less myopic eyes showed no significant difference between both groups (p = 0.555), but that of the more myopic eyes was significantly different (p = 0.027). Between both groups, the degree of anisometropia at 24 months was 3.61 ± 0.60 in group 1 and 4.20 ± 0.86 in group 2. Group 2 showed a significant difference and more severe anisometropic changes (p = 0.022). CONCLUSIONS: Full correction of myopic anisometropia without amblyopia is a better method for reducing the progression of anisometropia.

Analysis of Enhancement Rate According to Age after Refractive Surgery with Schwind Amaris

PURPOSE: To evaluate the clinical effects of an automatic energy-lowering system in patients over the age of 28 years with Schwind Amaris laser platform by analyzing the enhancement operation rate according to age. METHODS: A total of 20448 eyes from 10224 patients who received a bilateral LASIK or LASEK operation with the Schwind Amaris laser platform between August 2007 and April 2011 in our clinic were included in the present study. The rate of enhance operation due to undercorrection was analyzed to determine whether the age affects the enhancement operation rate. RESULTS: There were a total of 17 enhancement operations. Fifteen out of 17 eyes who received the enhanced operation were above the age of 28 years (p=0.005). In multivariate analysis, patient age over 28 years (OR=6.75, CI 1.54-29.60, p=0.011), preoperative higher spherical equivalent (OR=0.56, CI 0.41-0.77, p=0.0004) and preoperative higher mean keratometric value (OR=1.38, CI 1.01-1.88, p=0.043) were significantly associated with a higher enhancement operation rate. CONCLUSIONS: Surgeons should be aware that the amount of laser energy from Schwind Amaris laser platform is automatically reduced in patients above the age of 28 years. Therefore, the nomogram should be adjusted to reduce the enhancement operation rate for a specific age group, especially in patients with higher preoperative myopic errors and steeper cornea.

Comparison of Standard and undercorrected surgical methods for treating partially accommodative esotropia / 国际眼科杂志(Guoji Yanke Zazhi)

·AIM: To evaluate the efficacy of standard and undercorrected surgical methods in patients with partially accommodative esotropia (PAET).·METHODS: Twenty-five patients with PAET and normal accommodative convergence/accommodation ( AC/A )were divided into two groups for alternate surgical plan including standard method (13 patients) and under-corrected method (12 patients) in a randomized fashion.Standard method is based on measured deviation through full hyperopic correction at distant target and was performed by Parks scheme. Undercorrected method criteria is 20% lower than standard. All patients underwent symmetrical bilateral medial rectus recessions (BMR), and all of them were followed for 6 months.·RESULTS: Six months after operation, surgical success (defined as tropia =s 8A at distant and near fixation through full hyperopic correction) was 46% in standard group and 91% in undercorrected group. Overcorrection were observed 54% in standard group and 9% in undercorrected group (P＜0.05). There was no residual esotropia. There was no correlation between surgical success rate or overcorrection rate and age, mean of preoperative spherical equivalent or preoperative eye deviation.·CONCLUSION: Undercorrected BMR surgery has a lower overcorrection rate and higher surgical success rate than standard surgery in patients with PAET and normal AC/A.

Clinical Study for the Undercorrection Factor in Intermittent Exotropia

PURPOSE: The surgical technique for intermittent exotropia ?X(T)? is quite simple. However, in many cases, the condition recurs due to any one of a number of causes, including undercorrection. This study examined the factors associated with undercorrection on X(T) patients. METHODS: The study examined 199 X(T) patients who underwent bilateral recession of the lateral rectus muscle or unilateral recession of the lateral rectus muscle and resection of the medial rectus muscle, and who were followed-up for more than a year. Patients whose near and far distance angles of deviation were 9 prism diopters (PD) or more at one year after surgery were designated as group 1. Those whose PD was 8 or below or who had orthophoria were assigned to group 2. Various factors were compared and analyzed. RESULTS: One day after surgery, group 1 showed an average overcorrection of 1.9 and 4.1 PD at near and far, respectively, and group 2 showed an average overcorrection of 6.3 and 7.6 PD at near and far, respectively. A statistically significant difference was observed between the two groups (p0.05). CONCLUSIONS: Of the many factors that might influence the surgical results of X(T) patients, the angle of deviation during the initial postoperative period is the most important factor.

Undercorrection of the Thoracolumbar Kyphotic Deformity in the Osteoporotic Spine Fractures / 대한척추외과학회지

STUDY DESIGN: A retrospective study. OBJECTIVES: To assess the efficiency of undercorrection and transpedicular screw fixation through a posterior approach in osteoporotic spine fractures with a thoracolumbar kyphotic deformity. SUMMARY OF LITERATURE REVIEW: The surgical treatment of osteoporotic spine fractures with a thoracolumbar kyphotic deformity requires extensive surgical procedures to obtain complete restoration of the sagittal alignment, but it has a few technical limitations due to insufficient mechanical stability at the bone-screw interface. A special strategy is essential for transpedicular screw fixation for osteoporotic spine fractures with a thoracolumbar kyphotic deformity. MATERIALS AND METHODS: We reviewed 14 osteoporotic spine fracture cases, with a thoracolumbar kyphotic deformity, which had undergone undercorrection and transpedicular screw fixation through a posterior approach, between March 2000 and June 2003, with an average follow-up period of 15. 2 months. According to the Jikei grade of the osteoporosis, 9 and 5 cases were grades 2 and 3, respectively. As a radiographic assessment, we measured the kyphotic angles of the fused segments on the preoperative, postoperative and last follow up thoracolumbar lateral views on standing using Cobb's method, and also assessed the kyphotic angle correction (KAC). The clinical results were evaluated at the last follow-up. RESULTS: The kyphotic angles at the preoperative, postoperative and last follow-up were 33.5 degrees +/- 9.3, 22.4 degrees +/- 6.9 and 24.7 degrees +/- 6.8, respectively. We obtained a mean KAC gain of 11.1 degrees postoperatively (p0.05). The clinical results were analyzed as good, fair and poor in 8, 5 and 1 case, respectively. Fusions were achieved in all cases. CONCLUSIONS: Undercorrection and transpedicular screw fixation for a thoracolumbar kyphotic deformity in osteoporotic spine fractures can be one of the alternatives to avoid fixation failure and an extensive surgical procedure.

Evaluation of the Ocular Cyclotorsion During Laser in Situ Keratomileusis

PURPOSE: To evaluate the presence, degree and direction of ocular cyclotorsion in eyes undergoing laser in situ keratomileusis (LASIK). METHODS: We measured the presence, degree and torsional direction of 161 eyes of 88 patients who underwent LASIK for myopic and hyperopic astigmatism with LADARVision 4000 excimer laser (Alcon Summit Autonomous). Preoperatively, each eye was marked at the 3, 9-o'clock conjunctival area with marking pen under the slit lamp observation with a horizontal beam while the patient was seated upright. After lifting of corneal flap and acquiring of LADARVision4000 auto-tracking system, the presence and torsional direction was confirmed on the computer monitor and the rotational deviation degree was measured from horizontal reference line by software program built in laser computer system before the laser exposure. RESULTS: There was a cyclotorsional deviation in 144 eyes (89%). The counter-clockwise rotation was shown in 99 eyes (69%) and clockwise rotation in 45 eyes (31%). Mean ocular torsional misalignment was 3.8 +/- 2.9 degrees (right eye; 4.7 +/- 2.9 degrees, left eye; 3.5 +/- 2.4 degrees). 85 eyes (53%) had a torsional deviation less than 4 degrees and 5 eyes (3%) had a deviation greater than 10 degrees. CONCLUSIONS: A misalignment of astigmatism axis caused by ocular cyclotorsion was known as a reason of astigmatism undercorrection during LASIK. Thus, preoperative marking on conjunctiva and cyclotorsional axis alignment before laser treatment may reduce the incomplete astigmatism correction in LASIK.

Clinical Results of LASIK Enhancement

PURPOSE: To assess the results of laser in situ keratomileusis (LASIK) enhancement by lifting the original flap and reablation for the treatment of myopic regression and undercorrection after initial LASIK. METHODS: We analyzed LASIK enhancement results in 19 patients (27 of 1026 eyes) which had myopic regression or undercorrection after initial LASIK. We evaluated the changes of refractive error, uncorrected visual acuity, best corrected visual acuity, corneal topography, and corneal thickness before and six months after enhancement. We also analyzed enhancement rate according to the original refractive error. RESULTS: Overall, the mean spherical equivalent (SE) was -7.10+/-1.78 diopters (D) before LASIK, -2.80+/-0.79D prior to enhancement and -0.31+/-0.46D at 6 months after enhancement (p<0.001). The uncorrected visual acuity at 6 months after enhancement was 1.0 or better in 10 eyes (37.0%) and 0.5 or better in 27 eyes (100%). Best corrected visual acuity (BCVA) did not change in 12 eyes (44.4%) and improved 1 line or more in 9 eyes (33.3%) at 6 months after enhancement. The final refractive error of one group which underwent enhancement within postoperative 3 month was closer to emmetropia than that of the other which had enhancement after postoperative 3 month, but there was no statistically significant difference (p=0.589). CONCLUSIONS: LASIK enhancement by using the original flap was an effective procedure, if the changes of refractive error were stable on refraction or corneal topography.

The Effect of Reablation on the Undercorrected Eye after LASIK

We evaluated the effect of the reablation on the undercorrected eye after the Laser in-situ keratomileusis [LASIK]. The subjects were 21 eyes of 19 patients, who showed undercorrection after the LASIK. Reablation was done on the stromal bed after lifting the original flap aside. Patients were followed up for 1 to 6 months after the reablation. At the time of first LASIK, the mean spherical equivalent[S/E]was -11.29 +/-2.98D preoperatively, -1.90 +/-1.16D at postopera-tive 3 months, the mean amount of correction was -9.60 +/-1.90D. At the time of reablation, the mean[S/E]was -3.26 +/-1.08D, and the mean amount of correction was -3.31 +/-1.11D. Reablation was done only after the refractive error stabilized and did not change over 3 months. One month after the reablation, the mean[S/E]was +0.15 +/-0.98D and 85.7%of the eyes were within +/-1.0D. Six months after the reablation, the mean[S/E]was -0 .1 0 +/-0.66D and 84.6% were within +/-1.0D. The uncorrected visual acuity of 0.6 or more was achieved in 76.2%of eyes at 1 month, and 84.6%at 6 months. The best spectacle-corrected visual acuity [BSCVA]was lost 2 lines or more in 14.3%at 1 month, but none at 6 months after surgery. The BSCVA did not change or gain 1 line or more in 76.2%at 1 month, and 92.3%at 6 months after surgery. There was no problem when lifting the original corneal flap. In conclusion, reablation using the original flaps without new cuts seems to be a redictable, safe method for retreatment.

Overcorrection, Undercorrection and Astigmatic Change after Excimer Laser Photorefractive Keratectomy of Myopia

We have studied the overcorrection, undercorrection, astigmatic change and its incidence on time sequence after the excimer laser photorefractive keratectomy, and its relation with the degree of preoperative myopia, sex, and age. The study has been done with 429 eyes which we could assess for 6 months or more after excimer laser photorefractive keratectomy of myopia from July 1993 to march 1997. Overcorrection of more than -1D was common during the early postoperative periods and then gradually decreased with time. Overcorrection has been seen in 261 eyes(60.84%) after 1 month, but only 33 eyes(13.47%) after 1 year, and 13 eyes(11.02%) after 2 years. Undercorrection has been seen in 2 eyes(0.47%) after 1 month, but 25 eyes(10.20%) after 1 year, and 20 eyes(16.95%) after 2 years. Surgically induced astigmatism increased to 0.54+/-0.84D after 10 days and then decreased 0.19+/-0.75D after 12 months. Also, surgical induced astigmatism developed 1.13+/-1.10D in 247 eyes (57.58%) after 1 month, but decreased 0.89+/-0.45D in 107 eyes(43.67%) after 12 months. The occurrence of overcorrection and undercorrection was related to the severity of preoperative myopia(p0.05). The amount of postoperative astigmatism was related to preoperative astigmatism(p0.05).

The Surgical Outcome of Intermittent Exotropia and the Prognostic Factors

Surgical results of intermittent exotropia have been reported variabiy according to the criteria of surgical success and the length of follow-up.There have been also controversies about the factors affect the surgical outcoine of intermittent exotropia The surgical outcome and the factors which may affect the surgical results were retrospectively investigated in 165 patients who had undergone surgery for intermittent exotropia with at least 6 months (average 16.6 months, range 6-60 months) of post-operative follow-up.A `satisfactory result` , defined as a final alignment of orthophoria,esotropia less than 5PD or exotropia less than 10PD at far primary position,was achieved in 123 patients (74.5%). The diplopia at. postoperative one day tended to ensure 8 more satisfactory result (P0.05).

The influence of fusional divergence on the surgical results in intermittent exotropia

We investigated the influence of fusional divergence on the surgical results in the intermittent exotropia. Among the 56 patients with intermittent exotropia. the angle of deviation was measured during the preoperative period and the postoperative periods. The amplitude of the fusional divergence was measured with the rotary prism after the correction of the angle of deviation with the prism before the surgery. The subjects were devided into 4 groups; group one which returned to orthophoria after the overcorrection of exodeviation; group two - which did not return to orthophoria after the overcorrection of exodeviation; group three - which remained orthophoria after the correction of exodeviation; group four - which showed orthophoria initially but returned to undercorrection. There was not any significant difference between the four groups. We concluded that the influence of fusional divergence on the surgical results for intermittent exotropia was not significant enough. However, further studies should be done with more subjects for better results.