Comparative study of functional optical zone:small incision lenticule extraction versus femtosecond laser assisted excimer laser keratomileusis

AIM:To investigate the size of functional optical zone(FOZ)after small incision lenticule extraction(SMILE)versus femtosecond laser assisted excimer laser keratomileusis(FS-LASIK)for myopia correction and potential associated factors for FOZ.METHODS:A total of 133 patients who received corneal refractive surgery in our hospital between November 2018 and July 2021 were retrospectively enrolled.There were 63 patients(123 eyes)in SMILE group and 70patients(139 eyes)in FS-LASIK group.The size of FOZ was measured using Pentacam 3-dementional anterior segment analyzer before and 3mo after surgery,so as to analyze postoperative achieved functional optical zone(AFOZ)and its contributing parameters.RESULTS:When planned functional optical zone(PFOZ)was 6.5 mm for both groups,AFOZ was 1.45±0.27 and 1.67±0.25 mm smaller than preoperative FOZ in SMILE group and FS-LASIK group 3mo after surgery.AFOZ in SMILE group was significantly larger than that in FS-LASIK group(P<0.001).Variation of FOZ was negatively correlated with preoperative spherical equivalent(SE)and positively correlated with variation of mean keratometry value(△Km),variation of spherical aberration(△SA),and variation of Q-value(△Q,all P<0.001)in both groups.Multiple variable linear regression equations were△FOZ=1.354-0.1×pre-SE+0.336×△Q+1.462×△SA in SMILE group and△FOZ=1.512+0.137×△Q+0.468×△SA in FS-LASIK group.CONCLUSION:AFOZ is significantly smaller than preoperative FOZ in both SMILE and FS-LASIK groups.With the same PFOZ,larger AFOZ is achieved in SMILE group than in FS-LASIK group.

DIOPTER REGRESSION ANALYSIS OF LASER IN SITU KERATOMILEUSIS IN THE TREATMENT OF MYOPIA

Objective To evaluate the relevant factors of regression phenomenon of laser in situ kerato-mileusis (LASIK) for treatment of myopia. Methods We studied 408 eyes of 250 myopic patients who received LASIK. Patients were divided into 2 groups according to preoperative diopters (- 6 .00D- -10 .00D, 194 eyes;-10.10D- -15 .00D, 214 eyes). Mean period of follow-up were 12 months and the results were statistically analyzed. Results 12 months after surgery, in the first group (- 6.00--10.00D) the regressionequal to or beyond -1 .0D were 21 eyes (10.8%), range from -1 .0D to - 3 .0D. The average regression was -1.33D. In the second group (- 10 .10D - - 15 .00D) regression equal to or beyond -1.0D were 78 eyes (36.5%), range from -1 .0D to -5.50D. The average regression was -1 .99D. Conclusion The results indicate that excimer LASIK can be used to treat myopia between -6 .00D-- 15 .00D effectively with minimal regression within 12 months. Preoperative thin corneas with intraoperative small ablation zone could induce regression . Some modification of the surgical algorithms and laser nomogram will help to improve predictability and reduce regression.

ONE YEAR RESULTS OF LASER IN SITU KERATOMILEUSIS FOR CORRECTION OF HYPEROPIA

Objective: To evaluate the effectiveness, predictability and city of laser in situ keratomileusis (LASIK) for correction of hyperopia. Methods 54 eyes of 35 patients with hyperopia ranging from+1.00 to + 6. 00 diopter(D) received a one-pass, multizone scanning excimer laser ablations using the Chiron Technolas Keracor 11 7C excimer laser and System ALK automated corneal shaper H-230.Data on uncorrected and hot corrected visual acuity, predictability, stability of refraction, and complications were analyzed. The average follow-up was 12 months. Results At 12 months, the average residual refraction was(+ 0. 29 ±0. 78)D. 45 eyes (83.3% ) were in the range of ±1. OD and 33 eyes(61. 1% ) were within the range of ± 0. 5D. 50 eyes (92. 6% ) had uncorrected visual acuity of 20/40 or better and 34 eyes (63. 0% ) had 20/20 or better. 1 eyes (1. 9% ) lost 2 line of the best-corrected visual acuity and 2 eyes (3. 7% ) gained 2 lines or more. 2 eyes (3. 7%) had complaint of halos and 1 eyes (1. 9% ) had glare at 12 months. Conclusion LASIK can he used to treat hyperopia from + 1. 0D to + 6. 0D with good predictability and city. Primary and second hyperopia should he treated with different nomogram. some modification of the surgical algorithms and laser nomogram will help to improve predictability and stability of outcome.

Long-term efficacy of excimer laser in situ keratomileusis in the management of children with high anisometropic amblyopia

Background Children with anisometropic amblyopia are often noncompliant with traditional treatment including spectacules and contact lenses. This study was to evaluate the long-term efficacy of excimer laser in situ keratomileusis （LASIK） for children with high anisometropic amblyopia. Methods A retrospective analysis of 24 children with high unilateral anisometropic amblyopia, who underwent LASIK during the period between August 2000 and September 2005 in our hospital, was conducted. The mean age of these children was （7.4±1.9） years （range 5-14 years） and the mean follow-up period was （33.3±14.2） months （range 18.5-74.2 months）. After LASIK, visual acuity, refraction and far or near stereoacuity were analyzed. Near stereoacuity was measured by the random-dot butterfly stereogram and the pre-school random-dot stereogram, while far stereoacuity was measured by the synoptophore with Yan＇s random-dot stereogram. Results Mean preoperative uncorrected visual acuity was 0.06±0.05, while mean postoperative uncorrected visual acuity was elevated to 0.43±0.33. Mean preoperative best-corrected visual acuity was 0.26±0.22, while mean postoperative best-corrected visual acuity was elevated to 0.67±0.40. For patients with myopic anisometropia, preoperative mean spherical equivalent refraction was （-8.01±2.70） D while postoperative value significantly reduced to （-1.32±2.47） D. For patients with hyperopic anisometropia, preoperative mean spherical equivalent refraction was （ 7.35±1.55） D while postoperative value significantly reduced to （3.30±0.86） D. These results demonstrated that there was statistical difference in these parameters between preoperative and postoperative tests. At the last follow-up, 20 patients had near stereoacuity, and the mean near stereoacuities measured by the random-dot butterfly stereogram and the preschool random-dot stereogram were （149.00±152.93）＂ and （201.05±235.94）＂, respectively. In contrast, 11 patients had far stereoacuity, and the mean far stereoacuity measured by the synoptophore was （210.91±217.51）. Three cases of patients developed mild corneal complications. Conclusion LASIK for the correction of high anisometropia in children with monocular amblyopia may be safe and effective, and this can help effectively conduct postoperative amblyopia training and improve the cure rate.