Journal of Ophthalmic and Vision Research
Volume:18 Issue: 1, Jan-Mar 2023

Currently, two major principles exist to create LASIK flaps: firstly, a strictly horizontal (2D) cut similar to the microkeratome-cut and secondly an angled cut with a “step-like” edge (3D). The strictly horizontal (2D) cut method can be performed using apparatus such as the low-energy FEMTO LDV Z8 laser and its predecessors which are specific to this type. Alternatively, the low-energy FEMTO LDV Z8 laser’s 3D flap design creates an interlocking flap-interface surface which potentially contributes toward flap stability. In addition, the FEMTO LDV Z8 offers flap-position adjustments after docking (before flap-creation). The current study analyzed precision, safety, efficacy, as well as patient self-reported pain and comfort levels after applying two different types of LASIK flap morphologies which were created with a low-energy, high-frequency femtosecond (fs) laser device.

A prospective, interventional, randomized, contralateral eye, single-center comparison study was conducted from November 2019 to March 2020 at the Hamburg vision clinic/ zentrumsehstärke, Hamburg, Germany. Eleven patients and 22 eyes received low-energy fs LASIK treatment for myopia or myopic astigmatism in both eyes. Before the treatment, the eyes were randomized (one eye was treated with the 2D, the other eye with the 3D method).

The mean central flap thickness one month after surgery was 110.7 ± 1.6 μm (2D) and 111.2 ± 1.7 μm (3D); P = 0.365 (2D vs 3D). Flap thickness measured at 13 different points resulted in no statistically significant differences between any of the measurement points within/between both groups; demonstrating good planarity of the flap was achieved using both methods. Despite not being statistically significant, the surgeons recognized an increase in the presence of an opaque bubble layer in the 3D flap eyes during surgery and some patients reported higher, yet not statistically significant, pain scores in the 3D flap eyes during the first hours after the treatment. Overall, safety- and efficacy indices were 1.03 and 1.03, respectively.

In this prospective, randomized, contralateral eye study, the low-energy fs laser yielded predictable lamellar flap thicknesses and geometry at one-month followup. Based on these results, efficacy and safety of the corresponding laser application, that is, 2D vs 3D, are equivalent.

To determine associated factors for keratoconus (KCN) in the Iranian population.

In this retrospective case-control study, 100 KCN patients and 200 age- and sex-matched individuals, who were either candidates for photorefractive keratectomy or healthy referrals from the Torfeh Eye Hospital, were included as the case and control groups, respectively. KCN patients were all registered at the Iranian National Registry of Keratoconus (KCNReg®). Demographic characteristics, patients’ symptoms and their habits, as well as systemic and ocular disorders were documented. Clinical examinations included best corrected visual acuity (BCVA) and refractive error measurements, biomicroscopic examination, and corneal imaging.

In this case group, the frequency of mild, moderate, and severe KCN was 38%, 28%, and 34%, respectively. Parental consanguinity (odds ratio [OR] = 1.758, P = 0.029), positive familial history in patients’ first degree (OR = 12.533, P < 0.001) and second degree (OR = 7.52, P < 0.001) relatives, vernal keratoconjunctivitis (OR = 7.510, P = 0.003), severe eye rubbing (OR = 10.625, P < 0.001), and systemic diseases including migraine, hypertension, and thyroid disease (OR = 6.828, P = 0.021) were found as associated factors for KCN. Lesser frequency of KCN was observed in patients with Fars ethnicity (OR = 0.583, P = 0.042), with higher levels of wealth indices (OR = 0.31, P < 0.001) and higher levels of education (OR = 0.18, P = 0.024).

Severe eye rubbing, vernal keratoconjunctivitis, parental consanguinity and positive familial history of KCN, low socioeconomic status, and low levels of education were significantly associated with KCN in our study population.

To study the alterations on the lenticules extracted after femtosecond (Femto) small incision lenticule extraction (SMILE) versus the corneal free cap removed using a microkeratome.

The visuMax (500 kHz; laser energy: 180 nJ) was used for small-incision lenticule extraction. Free caps from human cadaveric corneas were excised by microkeratome. The collected lenticules were examined with the light and transmission electron microscope (TEM) for histological analysis, DNA fragmentation was assessed by agarose gel electrophoresis, DNA damage was evaluated using comet assay, and corneal proteins secondary structure was assessed by Fourier transform infrared spectroscopy (FTIR).

Light microscopic examination showed the presence of more edematous stroma under Femto SMILE than under free cap with a percentage change of 101.6%. In the Femto SMILE group, TEM examination showed pyknotic keratocytes, disruption, and cavitation of the collagen arrays stromal area under Femto SMILE. The DNA fragmentation for the Femto SMILE group revealed one undefined band with a size of 1.1 Kbp. The comet assay analysis indicated the presence of 3% and 8.0% tailed cells for the free cap and Femto SMILE groups, respectively. The tail lengths were 1.33 ± 0.16 and 1.67 ± 0.13 µm (P < 0.01), the percentage of tail DNA was 1.41 ± 0.18% (P < 0.01) and 1.72 ± 0.15%, and the tail moments were 1.88 ± 0.12 AU and 2.87 ± 0.14 AU (P < 0.001) for the free cap and Femto SMILE groups, respectively. FTIR spectroscopy of the Femto smile group revealed disorders in the secondary and tertiary structure of the proteins.

Femto SMILE technique induced more structural changes, DNA fragmentation, DNA damage, and corneal proteins secondary structure alteration than those induced by a microkeratome cutting. These changes may be attributed to the deep penetration of high energy levels to the corneal layer. These findings may highlight the potential impact of the Femto SMILE on the cornea and the necessity for managing the laser parameters used.

To investigate and optimize the accuracy of aphakic refraction (AR) techniques for secondary intraocular lens (IOL) power calculation in aphakic children.

Thirty-three aphakic eyes of 18 patients who were candidates for secondary IOL implantation were enrolled in the present study. Axial length (AL) measured by optical biometry was used in the biometric formula (SRK-T, Holladay II, and Hoffer-Q). AR and spherical equivalent (SE) were used in two AR-based formulas (Ianchulev, Leccissotti). True power was calculated based on postoperative SE at three months’ follow-up.

Regarding the postoperative SE, 13 (40%) eyes were within ±1.00 diopters (D) and 22 (66%) were within ±2.00 D. Median absolute error (MedAE) was predicted to be 4.4 and 7.3 D with the use of Ianchulev and Leccissotti formulas, respectively. The corresponding value was 0.8 D with the biometric formula. All eyes were deemed to have myopic refraction when using the AR-based formulas except one eye with the Ianchulev formula. The coefficient of our modified formula was 1.7 instead of 2.01 in the Ianchulev formula. MedAE with the use of new formulae was 0.5 D and was comparable with the true IOL power (P = 0.22).

Both Ianchulev and Leccissotti formulas resulted in a significant myopic surprise in aphakic children aged between 4.5 and 14 years. The modified formula proved to determine a more accurate SE that is comparable with biometric formulas.

In this study, an algorithm based on deep learning was presented to reduce the retinal nerve fiber layer (RNFL) segmentation errors in spectral domain optical coherence tomography (SD-OCT) scans using ophthalmologists’ manual segmentation as a reference standard.

In this study, we developed an image segmentation network based on deep learning to automatically identify the RNFL thickness from B-scans obtained with SD-OCT. The scans were collected from Farabi Eye Hospital (500 B-scans were used for training, while 50 were used for testing). To remove the speckle noise from the images, preprocessing was applied before training, and postprocessing was performed to fill any discontinuities that might exist. Afterward, output masks were analyzed for their average thickness. Finally, the calculation of mean absolute error between predicted and ground truth RNFL thickness was performed.

Based on the testing database, SD-OCT segmentation had an average dice similarity coefficient of 0.91, and thickness estimation had a mean absolute error of 2.23 ± 2.1 μm. As compared to conventional OCT software algorithms, deep learning predictions were better correlated with the best available estimate during the test period (r2 = 0.99 vs r2 = 0.88, respectively; P < 0.001).

Our experimental results demonstrate effective and precise segmentation of the RNFL layer with the coefficient of 0.91 and reliable thickness prediction with MAE 2.23 ± 2.1 μm in SD-OCT B-scans. Performance is comparable with human annotation of the RNFL layer and other algorithms according to the correlation coefficient of 0.99 and 0.88, respectively, while artifacts and errors are evident.

Adenosine signaling modulates ocular inflammatory processes, and its antagonism mitigates neovascularization in both newborns and preclinical models of ocular neovascularization including age-related macular degeneration (AMD). The adenosine receptor expression patterns have not been well characterized in the human retina and choroid.

Here we examined the expression of adenosine receptor subtypes within the retina and choroid of human donor eyes with and without AMD. Antibodies specifically targeting adenosine receptor subtypes A1, A2A, A2B, and A3 were used to assess their expression patterns. Quantitative real-time PCR analysis was used to confirm gene expression of these receptors within the normal human retina and choroid.

We found that all four receptor subtypes were expressed in several layers of the retina, and within the retinal pigment epithelium and choroid. The expression of A1 receptors was more prominent in the inner and outer plexiform layers, where microglia normally reside, and supported by RNA expression in the retina. A2A and A2B showed similar expression patterns with prominent expression in the vasculature and retinal pigment epithelium. No dramatic differences in expression of these receptors were observed in eyes from patients with dry or wet AMD compared to control, with the exception A3 receptors. Eyes with dry AMD lost expression of A3 in the photoreceptor outer segments compared with eyes from control or wet AMD.

The ocular presence of adenosine receptors is consistent with their proposed role in modulation of inflammation in both the retina and choroid, and their potential targeting for AMD treatment.

Mutations in TCP-1 ring complex (TRiC) have been associated with Leber Congenital Amaurosis (LCA). TRiC is involved in protein folding and has 8 essential subunits including CCT5. Herein, we studied the retina of TRiC mutant zebrafish to evaluate the possible role of impaired actin and tubulin folding in LCA.

The cct5𝑡𝑓 212𝑏 retina was histologically studied using Toluidine Blue staining as well as TUNEL, BrdU-labeling, and Phalloidin assays. Retinal organisation was assessed by quantification of the cellularity utilising DAPI.

Laminar organization of cct5𝑡𝑓 212𝑏 retinas was intact. Enhanced apoptosis throughout the cct5𝑡𝑓 212𝑏 retina was not compensated by higher proliferation rates, leaving the cct5𝑡𝑓 212𝑏 retina smaller in size. Quantification of retinal layer cellularity demonstrated that specifically the numbers of the amacrine and the retinal ganglion cells were depleted, suggesting that the cct5𝑡𝑓 212𝑏 retina was not uniformly affected by the reduced actin folding.

Whereas the current literature suggests that LCA is predominantly affecting retinal photoreceptor cells and the retinal pigment epithelium, cct5𝑡𝑓 212𝑏 analyses demonstrated the important role of folding of actin by TRiC, suggesting that cct5𝑡𝑓 212𝑏 is a useful tool to specifically analyze the role of F-actin filaments in the context of LCA.

This research intended to fabricate the thiolated chitosan-dextran nanoparticles (NPs) containing topotecan (TPH-CMD-TCS-NPs) to assess the ability of NPs in improving the efficacy of intravitreal chemotherapy of retinoblastoma in a rabbit xenograft model.

The coacervation process was used to produce the NPs. The cellular uptake of Cyanine-3 (CY3)-labeled NPs were investigated in human retinoblastoma Y79 cells using confocal microscopy. Also, the prepared TPH-CMD-TCS-NPs were tested in vitro by the tetrazolium dyes II (XTT) and flow cytometry in order to assess their cytotoxicity. In addition, a rabbit xenograft model of retinoblastoma was developed to test the antitumor effectiveness of TPH-CMD-TCS-NPs through intravitreal administration.

NPs had a mean diameter, polydispersity index, and zeta potential of 30 ± 4 nm, 0.24 ± 0.03 and +10 ± 3 mV, respectively. NPs (IC50s 40.40 compared to 126.20 nM, P = 0.022) were more effective than free topotecan as a dose-based feature. The tumor reaction to intravitreal chemotherapy with NPs was measured by evaluating the percentage of necrosis in the tumor tissue (91 ± 2%) and vitreous seeds (89 ± 9%) through hematoxylin and eosin (H&E) staining. In comparison with the control group, the TPHCMD-TCs-NPs treated group showed a significant decrease in tumor volume seven days after the intravitreal injection (P = 0.039). No significant changes were found in the ERG parameters after the intravitreal injection of TPH-CMD-TCs-NPs or TPH (P > 0.05).

This investigation revealed definitive antitumor efficacy of TPH-CMD-TCSNPs by intravitreal administration in the rabbit xenograft retinoblastoma model.

To estimate the incidence and identify the factors affecting retinopathy of prematurity (ROP) in a rural tertiary hospital in Thailand.

This retrospective chart review included all infants screened for ROP. The study included all infants with gestational age (GA) ≤ 30 weeks or birth weight (BW) ≤ 1,500 gr or selected larger infants with an unstable clinical course. Retinal findings were classified according to the revised International Classification of ROP. Data were analyzed using univariate and multivariable logistic regression analyses.

Of the 113 screened infants, the incidences of any ROP and ROP requiring intervention were 17.7% and 8.8%, respectively. In univariate analysis, lower GA, lighter BW, total days of supplemental oxygen, days of continuous positive airway pressure (CPAP), presence of apnea, and intraventricular hemorrhage (IVH) were associated with the development of any ROP. In the stepwise multivariable logistic regression analysis, lighter BW, male gender, and bronchopulmonary dysplasia (BPD) were significant risk factors for the development of any ROP. Lower GA and being either a twin or triplet were significant risk factors for ROP requiring intervention. However, no antenatal condition was identified as a risk factor for ROP.

The incidence of ROP in rural tertiary hospitals was relatively high as compared with previously published data from urban tertiary hospitals. Lighter BW, male gender, and BPD were significantly associated with the development of ROP in a local context. Epidemiological studies are necessary to prevent ophthalmic morbidities.

To evaluate the epidemiological features of open globe injury (OGI) in a tertiary ophthalmic center in the south of Iran.

The medical files of pediatric patients diagnosed with OGI between March 2014 and March 2019 were reviewed retrospectively. Demographic data, laterality, time of injury, cause of trauma, location and mechanisms, complications, and the involved tissues, visual acuity, type of operation, and antibiotic therapy were all analyzed. Data were processed using the SPSS.

In total, 110 eyes of 108 patients were included. Ages <7 years comprised 49.1%, 7–12 years 26.4%, and 13–18 years 24.5% of cases. Of the 108 patients, 76 (70.3%) were males. No significant difference between right versus left eyes was seen. The incidence of OGI was lowest in winter and highest in spring, and it had more prevalence on the weekends. Sharp objects were the most common cause of OGI in ages <7 years, while blunt objects, accidents and falls, and guns and fireworks were more prevalent in older children. Home was the most common place of injury overall. The most common type of injury was penetrating trauma. Upon arrival, most of the children had a visual acuity <0.1 decimal. Primary wound closure was the most prevalent type of surgery done predominantly within 24 hr from admission time.

Ages <7 years and male gender were the most common age and sex of pediatric OGI, respectively, and sharp objects were the predominant etiology. Early management and primary repair are essential for prevention of complications such as endophthalmitis and amblyopia.

Ophthalmology is one of the major imaging-intensive fields of medicine and thus has potential for extensive applications of artificial intelligence (AI) to advance diagnosis, drug efficacy, and other treatment-related aspects of ocular disease. AI has made impressive progress in ophthalmology within the past few years and two autonomous AIenabled systems have received US regulatory approvals for autonomously screening for mid-level or advanced diabetic retinopathy and macular edema. While no autonomous AI-enabled system for glaucoma screening has yet received US regulatory approval, numerous assistive AI-enabled software tools are already employed in commercialized instruments for quantifying retinal images and visual fields to augment glaucoma research and clinical practice. In this literature review (non-systematic), we provide an overview of AI applications in glaucoma, and highlight some limitations and considerations for AI integration and adoption into clinical practice.

Coronavirus disease 2019 (COVID-19) is a current pandemic caused by SARS-CoV-2 that has vastly affected the whole world. Although respiratory disease is the most common manifestation of COVID-19, the virus can affect multiple organs. Neurotropic aspects of the virus are increasingly unfolding, in so far as some respiratory failures are attributed to brainstem involvement. The neuro-ophthalmic manifestations of COVID-19 and the neuro-ophthalmic side effects of vaccination were reviewed. The major findings are that the SARS-CoV-2 infection commonly causes headaches and ocular pain. It can affect the afferent and efferent visual pathways by ischemic or inflammatory mechanisms. Optic nerve may be the origin of transient or permanent visual loss from papillophlebitis, idiopathic intracranial hypertension, or optic neuritis. Cerebrovascular strokes are not uncommon and may lead to cortical visual impairment or optic nerve infarction. SARSCoV-2 may affect the pupillomotor pathways, resulting in tonic pupil (Adie’s syndrome) or Horner’s syndrome. Cranial neuropathies including third, fourth, sixth, and seventh nerve palsies have all been reported. Rhino-orbital mucormycosis superinfections in COVID-19 patients receiving steroids or other immunosuppressive therapies may result in unilateral or bilateral visual loss and ophthalmoplegia. Autoimmune conditions such as GuillainBarré, Miller-Fisher syndrome, and ocular myasthenia have been reported.

To describe a new method of treatment of corneal perforation with extensive corneoscleral melt.

Case Report: 

A 42-year-old man presented with moderate-sized (3.5 mm) corneal perforation with extensive corneo-limbo-scleral ulceration following bare sclera excision of pterygium. No prior use of antimetabolites or postoperative beta radiation noted. We considered retrocorneal sclera patch supported cyanoacrylate application. The sclera was thinned to one-third thickness and a patch (4.5×4.5 mm) was punched. The sclera patch was placed on the iris, behind the corneal perforation, adequately covering it from inside. A minimal amount of adhesive was applied on the retrocorneal sclera patch and margin of corneal perforation. The ulcerating sclera was covered with double layered amniotic membrane. Topical antibiotic, steroid, and cycloplegic drops were instilled thrice daily. Corneal perforation healed and no recurrence occurred during the 18 months’ follow-up.

Retrocorneal scleral patch supported cyanoacrylate is effective for corneal perforation with corneo-scleral melt.

To demonstrate novel treatments for patients with high juvenile xanthogranuloma ( JXG) eyelid lesion burden.

Case Report: 

A 14-year-old girl was referred to the oculoplastic surgery service for management of worsening extensive bilateral eyelid and adnexal lesions in the setting of JXG. The patient underwent intra-lesional steroid injections, serial excisions, and reconstruction with skin grafts. She was subsequently treated with CO2 laser-assisted topical steroid application, which resulted in lesion regression.

A novel multimodal approach to treatment of severe periocular JXG, incorporating surgical debulking, skin autograft, CO2 laser, and intra-lesional steroids, can be effective for lesion control.