OBJECTIVE: To evaluate the safety, efficacy and postoperative visual quality of small incision lenticule extraction (SMILE) and Wavefront-Guided Laser in situ keratomileusis (WFG-LASIK) and to analyze their efficacy in correcting astigmatism.
METHODS: A systematic literature search was performed using Cochrane Collaboration methodology. Databases searched included PubMed, Embase, the Cochrane Library and Web of Science. RevMan software version 5.3.0 was used for meta-analysis.
RESULTS: A total of 976 eyes were included in 8 studies, of which 539 eyes underwent SMILE and 437 eyes underwent WFG-LASIK. There were no statistically significant differences in the proportion of eyes achieving uncorrected distance visual acuity of 20/20 or better (P=0.18), the proportion of eyes within±0.50 diopter of target refraction postoperatively (P=0.10), or the postoperative magnitude of cylinder (P=0.10). Regarding the Alpins vector analysis of astigmatism, there was no statistically significant difference in the surgical magnitude of error (P=0.09) between the two groups. WFG-LASIK has a lower surgical angle of error (P= 0.002) and higher surgical correction index of cylinder (P=0.03) than SMILE. In terms of aberrations, higher order aberrations (P=0.46), spherical aberrations (P=0.22) and trefoil (P=0.56) were not statistically different, while WFG-LASIK induced less coma than SMILE surgery (P=0.02).
CONCLUSIONS: Both SMILE and WFG-LASIK are safe and effective ways to correct myopia and astigmatism. Compared with SMILE, WFG-LASIK has a lower surgical angle of error, higher surgical correction index of cylinder and induces less coma.

OBJECTIVE: To study the influence of tropical endemic limboconjunctivitis (TELC) on the distribution of astigmatism in a population of black children.
METHODS: We matched two groups of 36 children between the ages of 3 and 15 by age and sex. Group 1 consisted of children with TELC, and group 2 was made up of controls. All underwent cycloplegic refraction. The studied variables were age, sex, type and stage of TELC, spherical equivalent, absolute cylinder value and clinical type of astigmatism. The odds ratio was used to quantify the link between TELC and astigmatism. We used the Chi2 test for the comparison of qualitative variables and the Student T test for the comparison of the means of quantitative variables. The threshold of significance of the differences was set at 0.05.
RESULTS: Astigmatism was more common in children with TELC (61.97% vs. 37.5%), (OR=1.53; 95% CI 1.08-2.15; P=0.012). The history of TELC was associated with an increased risk of with-the-rule astigmatism (OR 1.91; 95%CI (1.23-2.97).
CONCLUSIONS: Pediatric TELC is frequently associated with the with-the-rule astigmatism in our practice setting.

OBJECTIVE: To evaluate refractive, aberrometric, topographic, and topometric outcomes of asymmetric intracorneal ring segment (ICRS) implantation in snowman phenotype (asymmetric bow-tie) keratoconus.
METHODS: This retrospective, interventional study included eyes with snowman phenotype keratoconus. Two asymmetric ICRSs (Keraring AS) were implanted after femtosecond laser-assisted tunnel formation. Visual, refractive, aberrometric, topographic, and topometric changes after asymmetric ICRS implantation were evaluated with a mean follow-up of 11 months (6-24 months).
RESULTS: Seventy-one eyes were analyzed in the study. Keraring AS implantation corrected refractive errors significantly. The mean spherical error decreased from -5.06±4.23 D to -1.62±3.45 D (P=0.001), and the mean cylindrical error decreased from -5.43±2.48 D to -2.44±1.49 D (P=0.001). Uncorrected distance visual acuity improved from 0.98±0.80 to 0.46±0.46 Log MAR (P=0.001), and corrected distance visual acuity improved from 0.58±0.56 to 0.17±0.39 Log MAR (P=0.001). Keratometry (K) maximum, K1, K2, K mean, astigmatism, and corneal asphericity (Q-value) showed a significant decrease (P=0.001). Vertical coma aberration decreased significantly from -3.31±2.12μm to -2.56±1.94μm (P=0.001). All topometric indices of corneal irregularities were significantly reduced postoperatively (P=0.001).
CONCLUSIONS: Keraring AS implantation in snowman phenotype keratoconus demonstrated good efficacy and safety. Clinical, topographic, topometric, and aberrometric parameters improved significantly after Keraring AS implantation.

OBJECTIVE: To investigate the changes in refractive status of amblyopic patients with partially refractive esotropia (PAET).
METHODS: Amblyopic patients with PAET were enrolled. Non-amblyopic patients with full refractive accommodative esotropia (RAET) were included in the study as a control group. Preoperative and postoperative best-corrected visual acuity (BCVA), spherical equivalent (SE), astigmatism, stereoacuity, and deviations at near and distance were evaluated and statistically compared within the study group. Mean BCVA, SE, astigmatism were compared between the two groups.
RESULTS: The patient and the control groups were composed of 58 eyes of 29 patients per group. There were statistically significant differences between pre- and postoperative mean astigmatism and SE between the patient and control groups. The mean astigmatism was higher in amblyopic eyes when compared with the eyes in the control group (P:0.009). During the follow-up period, changes in SE and astigmatism were not different between groups.
CONCLUSIONS: The mean SE and astigmatism were changed in both amblyopic patients with PAET and non-amblyopic patients with RAET during the follow-up period. This suggested that neither amblyopia nor strabismus surgery has an effect on refractive status in patients with PAET.

OBJECTIVE: Intraocular lens (IOL) calculation and biometry have evolved significantly in recent decades. However, present outcomes are still suboptimal. Our objective is to summarize the results reported in the literature with regard to a new variable, the value of the relationship between anterior and posterior corneal curvature in the biometric calculation of IOL power.
METHODS: We have created a narrative revision of the existing evidence regarding the posterior to anterior corneal curvature ratio in IOL calculation.
RESULTS: The corneal posterior/anterior ratio (P/A ratio), also called Gullstrand ratio, has a standard deviation of 2.4% in normal people, hence causing a possible IOL power miscalculation error of up to 0.75 diopters (D). This error is magnified in pathological corneas or in those with previous refractive surgery. Including the P/A ratio in the IOL formula reduces errors in the calculation of IOL power.
CONCLUSIONS: Measurement of the posterior corneal surface should be recommended prior to IOL calculation, given the demonstrated results regarding the P/A ratio for IOL power calculation. Regarding toric IOL calculation, we suggest incorporation of all internal astigmatic vectors, for instance, posterior corneal surface, IOL tilt induced toricity, and retinal astigmatism. All of these factors may improve surgical outcomes.

OBJECTIVE: To determine whether manifest refractive astigmatism (RA) or anterior corneal astigmatism (CA) is the best value for excimer laser programming in cases of ocular residual astigmatism (ORA).
METHODS: Patients who had undergone LASIK surgery with a disagreement between manifest refractive and corneal cylinder (ocular residual astigmatism ORA)>0.75 D were included retrospectively in this study. We calculated target induced astigmatism vector (TIA), surgically induced astigmatism vector (SIA), difference vector between the astigmatism correction programmed in the excimer laser and refractive astigmatism (DVRA), difference vector between the astigmatism correction programmed in the excimer laser and corneal astigmatism (DVCA) and difference vector between TIA and SIA (DV), by the Alpins method. Vectorial differences between DV and DVRA, and between DV and DVCA, were then calculated to determine whether RA or CA was closest to the ideal cylinder for laser programming.
RESULTS: Of a total of 104 eyes undergoing LASIK, 22 eyes of 12 patients (21.1%) had an ORA>0.75 D and were included. Mean ORA was 0.9±0.2 D and mean postoperative subjective cylinder was 0.45 D. The DV-DVRA difference vector was 0.57±0.2 D, and the DV-DVCA difference vector was 0.86±0.4 D (P=0.02). RA was closer than CA to the ideal astigmatism correction.
CONCLUSIONS: In cases of discrepancy between manifest astigmatism and corneal astigmatism, correction of manifest refractive astigmatism seems to give a better refractive result.

OBJECTIVE: To describe ocular biometric parameters and the prevalence of corneal astigmatism as well as age and gender correlations in a population of cataract surgery candidates and to estimate the number of eyes that would be candidates for a toric intraocular lens (IOL).
METHODS: In consecutive patients requiring cataract surgery over a one-year period (June 2016 to June 2017), the following optical biometry measurements were performed on an IOLMaster 700 or Lenstar 900: axial length (AL), anterior chamber depth (ACD), lens thickness (LT), mean keratometry (K), flat keratometry (K1), steep keratometry (K2), corneal astigmatism (Cyl) and white-to-white diameter (WTW). Descriptive statistics for the demographic and biometric data were analyzed.
RESULTS: The study sample included 6111 eyes of 3332 patients (59.3% women), with a mean age of 74.78±9.7years. The means of the compiled data are as follows: AL 23.58±1.55mm, ACD 3.08±0.41mm, LT 4.55±0.52mm,K 44.15±1.54 diopters (D), K1 43.64±1.57 D, K2 44.69±1.61 D, Cyl 1.0±0.81. D and WTW 11.88±0.46mm. The male patients had significantly larger eyes (higher AL, ACD and WTW) and flatter corneas (lower flat and steep K). Older patients had significantly lower AL, ACD and WTW, while their LT values were higher. Corneas became significantly steeper with age. 60.5% of eyes had less than 1 D of corneal astigmatism, while 3.1% had ≥3.0 D.
CONCLUSIONS: Less than 1 D of corneal astigmatism was present in the majority of cataract surgery candidates. 3.1% of eyes were candidates for a toric IOL. This study provides useful information on inventory requirements for planning hospital resources.

OBJECTIVE: To study the efficacy, stability, safety and predictability of small incision lenticule extraction (SMILE) at 1 day and 3 months postoperatively for moderate and high myopic astigmatism. To describe a simple and convenient method for detection and manual compensation of cyclotorsion during the procedure.
METHODS: In this retrospective study, a total of 164 eyes from 114 patients over 20 years of age with at least 1.5 diopters (D) of myopic astigmatism were treated by SMILE. Any cyclotorsion was manually compensated by gently rotating the cone to align the horizontal marks on the cornea to the 0° to 180° axis of the reticule after activating the suction.
RESULTS: The mean preoperative spherical equivalent (SE) was -5.3±2.01 D, and the mean cylinder was -2.01±0.67 D. Three months after surgery, a total of 87% of eyes were within±0.50 D of attempted post-operative SE, and 98% of eyes were within±1.00 D. Overall, the predictability of cylinder correction was excellent, with 96.3% of eyes within±1.00 D of attempted post-operative cylinder. The mean postoperative cylinder at three months was -0.3±0.39 D. We noted a slight undercorrection with treatment of high cylinder. However, 82% of eyes achieved postoperative refractive astigmatism less than 0.5 D. 91% of eyes achieved uncorrected distance visual acuity (UDVA) equal to or better than 8/10. 22% of eyes gained one line of visual acuity.
CONCLUSIONS: SMILE is a predictable and safe technique for the surgical correction of astigmatism. Manual compensation may be an effective approach to improve astigmatic outcomes of SMILE, especially in moderate and high astigmatism.

OBJECTIVE: A certain number of conditions can result in compromised anterior and/or posterior capsular integrity. Several surgical options have been employed for repositioning dislocated intraocular lenses in the absence of adequate capsular support. The purpose of this study is to assess the functional outcomes and complication profile of a modified surgical technique for replacing dislocated intraocular lenses.
METHODS: All patients who had undergone the modified surgical procedure for dislocated intraocular lenses between 2012 and 2017 were retrospectively reviewed for visual outcomes and complications. Patient demographic characteristics, pre- and postoperative visual acuity, surgical indications, refractive outcomes, intraocular pressure and postoperative complications were recorded and analysed at baseline and at six months, which was the conclusion of the study. We also present our modified surgical technique.
RESULTS: Sixty-eight eyes of sixty-eight patients (74% male) were included. Mean age at surgery was 58 years (range 4-89 years). Mean best-corrected visual acuity increased significantly from 0.80 (SD±0.2) LogMar to 0.40 (SD±0.1) LogMar (P<0.005). Median astigmatic error at the conclusion of follow-up remained stable. There were no intraoperative complications and a low postoperative complication rate (10.2%), mainly related to the surgical context.
CONCLUSIONS: Sutureless intrascleral fixation of dislocated intraocular lenses is an option in case of deficient capsular support. Visual outcomes and complication rates are comparable to other case series.

OBJECTIVE: To determine the indications, frequency, influential factors and clinical outcomes of resuturing in an atraumatic setting after penetrating keratoplasty (PK).
METHODS: Medical records of all patients who underwent resuturing in the absence of traumatic wound dehiscences after PK between January 1, 2007 and December 31, 2015 were reviewed. The cases were divided into 2 groups: patients with suture-related problems underwent mandatory resuturing (mandatory group), and patients with post-PK ectasia or a progressive increase in K values and surgically induced astigmatism underwent optional resuturing (Optional group). Patient demographics and surgical indications for PK, reasons for and frequency of resuturing, time between PK and resuturing, and clinical outcomes were evaluated.
RESULTS: The frequency of resuturing was 9.03% (59 of 633), and the mean age was 39.15±17.80 years. The most common indication for PK was keratoconus (42.4%) and the interval between PK and resuturing ranged from 0.03 to 32 months. The underlying cause leading to resuturing was suture-related problems in 43 eyes (72.9%), development of ectasia or progressive steepening of the K values and surgically induced astigmatism in 16 eyes (27.1%). The mean visual acuity increased, the K value and astigmatism decreased significantly following resuturing in both the mandatory group and the Optional group (P≤0.2). The decrease in astigmatism and K values was more marked in the Optional group, as expected (P≤0.001).
CONCLUSIONS: While resuturing is essential in order to obtain wound integrity in the setting of dehiscence, it is effective in terms of achieving higher visual acuities and lower astigmatism and K values in high astigmatism and post-PK ectasia cases.