Medical Hypothesis, Discovery & Innovation in Optometry

Background: Ascorbic acid has been suggested to be effective in chemical burns. It has first been tested in rabbits, then it was implemented in human subjects and proved that it could be used in different treatments such as corneal chemical and thermal burns. Herein, we aimed to review the effects of ascorbic acid in the healing of chemical and thermal corneal burns.

Methods: Authors included an electronic search of MEDLINE, clinicaltrials.gov, and Google Scholar without time limit on English literature.  The final outcome after selection based on inclusion and exclusion criteria using keywords “Corneal Burn,” AND “Corneal Ulcer,” AND “Vitamin C,” yielded seventeen articles in English focused on the effect of vitamin C on corneal burn induced ulcer, either chemical or thermal.

Results: The seventeen related eligible studies that fulfilled the inclusion criteria included three retrospective nonrandomized comparative study on human subjects and fourteen in vivo laboratory-based studies on rabbits (12 studies), rat (one study), as well as guinea-pigs (one study). Most of the studies have shown benefits in using vitamin C as a prophylactic treatment that delays or stops corneal ulcer after chemical or thermal corneal burn.

Conclusions: Vitamin C is a very basic inexpensive prescription and can be used to treat corneal ulcers following a variety of corneal burns, regularly. Besides, this review highlights the necessity for conducting randomized controlled trials to investigate on the prophylaxis role of vitamin C and to determine its minimum required dose in the management of corneal ulcers following different kinds of corneal burns.

Background: This study was performed to evaluate long-term outcomes of sutureless scleral-fixated intraocular lens implantation at a tertiary referral center.

Methods: A retrospective observational analysis was performed on 50 consecutive patients who underwent sutureless scleral-fixated lens implantation by a single surgeon from January 2009 to December 2015. Indications for surgery were aphakia, dislocated intraocular lens (IOL) and lens with poor capsular support. Visual acuity, indication for surgery, ocular history, ocular comorbidities, intraoperative or postoperative complications and the need for further surgery were analysed.

Results: The study analysed data of 50 eyes from 43 patients with a mean ± standard deviation (SD) follow-up of 16.64 ± 9.34 months. Of these 50 eyes, 38 agreed for a telephonic interview. Mean ± SD follow-up for these patients was 25.12 ± 4.56 months. Final visual acuity was 6/18 or better in 39 eyes. Intra-ocular lens was stable and well centred in 48 eyes. IOL dislocation was noted in 2 eyes, retinal detachment in one eye, and worsening of diabetic cystoid macular oedema in one eye. Two patients with pre-existing corneal decompensation from complicated cataract surgery had worsening of their condition.

Conclusions: Sutureless scleral fixated intraocular lens could be considered as a long-term option for the management of aphakia, dislocated intraocular lens and lens with poor capsular support. However, future studies with more subjects, longer follow-ups, and robust study design are needed to confirm the results of the present study.

Background: To assess, evaluate, and compare outcomes of laser-assisted in situ keratomileusis (LASIK) versus optical spectacles correction in the treatment of anisometropia in adult patients we aimed to perform this study.

Methods: This prospective randomized controlled clinical trial included 50 eyes of 50 patients. We randomly distributed the participants into two groups comprise group A (experimental/LASIK group) consist of 25 eyes with anisometropia and assigned for LASIK treatment, as well as group B (control/spectacles group), consist of 25 eyes with anisometropia and allocated for optical spectacles correction. All patients underwent preoperative and postoperative visual acuity, subjective and cycloplegic refraction, fundus, slit-lamp, and corneal topography examinations.

Results: In group A, at one month postoperation, there were statistically significant differences in uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), refractive sphere, cylinder and spherical equivalent (SE). Three month postoperation, SE showed good stability within ±0.50 diopter (D) in 22 eyes (88%) and within ± 0.75D in 23 eyes (92%), while two eyes had an SE beyond 1.00D of emmetropia in group A. Five eyes revealed amblyopia with minimal improvement in two eyes in group A following LASIK and no improvement in three eyes treated with spectacles in group B. Two amblyopic eyes had developed ocular deviations at the end of the study that referred to the strabismus unit.

Conclusions: Our outcomes revealed that LASIK was more effective and more advantageous than spectacles in the treatment of different types of anisometropia in adults. However, future randomized trials with a focus on optical versus surgical treatment of anisometropia and anisometropic amblyopia in both pediatric and adult patients are needed to further confirm the conclusions of this study and enhance our confidence for generalizing this modality of treatment.

Background: Presbyopia is the normal progressive waning of accommodation with loss of the visual ability to focusing on objects reside different distances. Presbyopia triggers a cost in quality of life and professional efficiency of many people over 40. Presbyopia is likely to be one of the main pressing visual concerns of the 21st century, given that life expectancy increases and with it the aging of the population comes. This review aimed to address the three strategies of the pharmacological treatment for presbyopia.

Methods: A review on PubMed, Google Scholar, and Clinicaltrials.gov was performed to investigate the English literature on pharmacological treatment for presbyopia from 2012 to September 30, 2020.

Results: In addition to the treatment of presbyopia with glasses or contact lenses, new surgical strategies developed, some of them with success. However, during the last decade, a new promising not invasive option for treating presbyopia emerged called the pharmacological approach. Many researchers have developed three different lines of investigation from different assumptions on a pharmacological basis. The first consists of producing miosis, to take advantage of pharmacologically-induced pinhole effect, depth of focus increases and thus the uncorrected near visual acuity (UNVA) could be improved. The second aims to rehabilitate accommodation binocularly to enable good vision at all distances. Finally, the third development attempted to rehabilitate the lost elasticity of the human crystalline lens.

Conclusions: None of the three discussed strategies of the pharmacological treatment for presbyopia, prescribed globally, but patients of restoring accommodation strategy can adhere locally, where they are sold so far as master prescriptions.

Background: The effectiveness of cataract surgery depends on preoperative biometric data, including axial length (AL), keratometric value (K), anterior chamber depth (ACD), and the accuracy of Intraocular Lens Power (IOLp) calculation. To this date, five generations of calculating formulas have been developed. This review aimed to summarize the main formulas used to date, and focus on the calculating characteristics, advantages, and disadvantages of each one. Moreover, it compares the results of several formulas used in patients with specific characteristics.

Methods: The authors searched PubMed and Google scholar, using keyword combinations including IOL power (IOLp), formulas, axial length (AL), anterior chamber depth (ACD), keratometric value (K), diopters (D). Two hundred articles of the recent literature referring to IOLp calculation formulas and the effectiveness of each formula, when used preoperatively in cataract surgery, were retrieved and analyzed.

Results: Each generation of formulas carries their own advantages and disadvantages for the individual patient and selection of the appropriate IOL differs due to their different ALs. The shorter or the longer the eye is, the less accurate the formula used becomes. Although, formulas like SRK-T, Holladay, SRK-II, Hoffer and Binkhorst II seem to have the same effectiveness, there are studies indicating the superiority of Hoffer for short eyes. On the other hand, SRK/T appears to display a minor superiority for long eyes. Fifth generation formulas also appear to be very promising.

Conclusions: Based on the available literature, following the comparison of different generation formulas for specific eyes, there is no gold standard as yet for all cases. It is crucial to realize that every patient demands individualized management depending on special eye characteristics.

Background: The authors aimed to evaluate high-order aberrations (HOAs) after wavefront-guided laser in situ Keratomileusis (LASIK) and photorefractive keratectomy (PRK) in patients with myopia and myopic astigmatism.

Methods: In this retrospective observational case-control study patients who underwent wavefront-guided LASIK and PRK between August 2018 and November 2018 in refractive surgery unit in Kayseri City Hospital Eye Clinic, Turkey, were included. Thirty-eight eyes of 19 patients in the LASIK group and 40 eyes of 20 patients in the PRK group were included. The corrected distance visual acuity (CDVA), manifest refraction, corneal topography, and HOAs of the patients were evaluated preoperatively and 3 months postoperatively.

Results: The mean ± standard deviation (SD) of age of the patients was 27.13 ± 5.54, and 29.10 ± 4.38 years in the PRK and LASIK groups, respectively (P= 0.06), with CDVA of 1.00 in both. Mean ± SD of spherical and spherical equivalent values were -2.09 ± 1.56 diopter (D), -3.03 ± 1.72 D and -2.23 ± 1.69D, -3.35 ± 1.71 D, respectively in PRK and LASİK groups, respectively (P =0.58). When the preoperative and postoperative HOAs and root mean square (RMS) values (for 6 mm pupil diameter) were compared in the PRK group, a significant difference was found in vertical coma and total RMS values (P= 0.002, and P ˂0.001, respectively). In the LASIK group, there was a significant difference in preoperative and postoperative vertical coma and total RMS values (P= 0.003, P˂0.001). There was no significant difference in preoperative vertical coma and postoperative vertical coma values between two groups (P= 0.735, and P =0.583 respectively).

Conclusions: In terms of HOAs, total RMS values decreased significantly, and vertical coma values increased significantly in the third month postoperatively in both LASIK and PRK groups, yet no difference noted between them.