Background and Objective: Corneal neurotization is a novel surgical technique used to restore corneal sensation in patients with neurotrophic keratopathy. Neurotrophic keratopathy is a disorder characterized by dysfunction of the ophthalmic division of the trigeminal nerve, which provides sensory innervation to the cornea. Without sensation, the cornea is at risk of infection, ulceration, perforation, and ultimately, vision loss. Corneal neurotization has emerged as an innovative technique to reinnervate anesthetized corneas by transferring a healthy donor nerve to the affected eye around the corneoscleral limbus. As the field of corneal neurotization rapidly grows, there is a need to synthesize the existing body of literature on corneal neurotization and identify important areas for further research. In this review, we will discuss neurotrophic keratopathy and its current management strategies, followed by an overview of corneal neurotization techniques, outcomes, surgical considerations, and future directions. Methods: PubMed and Google Scholar searches were conducted to retrieve and analyze relevant original papers and reviews on neurotrophic keratopathy and corneal neurotization up until April 2022.Key Content and Findings: Currently, numerous techniques for corneal neurotization exist, including direct nerve transfers, as well as indirect neurotization via interposition nerve grafts. So far, corneal neurotization has been shown to be highly successful in restoring corneal sensation, improving visual acuity,and improving corneal epithelial health. To date, there have been no significant differences in outcomes between direct versus indirect neurotization techniques, different donor nerves, or autologous versus allogeneic interposition grafts. However, there is some evidence that corneal neurotization procedures may be more successful in pediatric patients.Conclusions: Corneal neurotization shows great promise in treating neurotrophic corneas and represents the first management option to date that addresses the underlying pathophysiological mechanism of neurotrophic keratopathy by restoring corneal sensation. As the use of corneal neurotization continues to broaden, additional studies will become important to compare techniques in a systematic manner, with larger sample sizes, as well as standardized outcome measures and follow-up time.

Background: To compare two swept-source optical coherence tomography (SS-OCT) biometers,IOLMaster 700 and ANTERION.

Methods: This is a retrospective study. Biometric measurements of cataract patients performed between March and July 2021 in the Department of Ophthalmology, United Christian Hospital, Hong Kong, were reviewed. Patients scheduled for cataract surgery were measured with both SS-OCT devices on the same day.The following biometry parameters were compared: keratometry (K), total keratometry (TK), axial length (AL), central corneal thickness (CCT), anterior chamber depth (ACD), lens thickness (LT), white-to-white (WTW) and the predicted intraocular lens (IOL) power to achieve emmetropia. To assess the agreement between the devices, Bland-Altman analysis with 95% limits of agreement (LoA) were used.

Results: In total, 92 eyes of 47 subjects were measured with both devices. There were statistically significant differences between the two biometers for most measurements (P<0.05) except for flat K, AL and IOL power when using the right eyes for analysis. For the left eyes, there were statistically significant differences in the measurements from the two biometers in all parameters except for flat and steep K. The ANTERION did not obtain ACD, AL and LT in 2 (2.17%), 1 (1.09%) and 5 cases (5.43%) respectively.

Conclusions: The two biometers showed a clinically acceptable agreement in most parameters. Comparisons showed significant differences in most parameters but not clinically relevant except for the TK and WTW, and these two parameters should not be used interchangeably between the devices.

Background: A variety of experimental animal models are used in basic ophthalmological research to elucidate physiological mechanisms of vision and disease pathogenesis. The choice of animal model is based on the measurability of specific parameters or structures, the applicability of clinical measurement technologies, and the similarity to human eye function. Studies of eye pathology usually compare optical parameters between a healthy and altered state, so accurate baseline assessments are critical, but few reports have comprehensively examined the normal anatomical structures and physiological functions in these models.

Methods: Three cynomolgus monkeys, six New Zealand rabbits, ten Sprague Dawley (SD) rats, and BALB/c mice were examined by fundus photography (FP), fundus fluorescein angiography (FFA), and optical coherence tomography (OCT).

Results: Most retinal structures of cynomolgus monkey were anatomically similar to the corresponding human structures as revealed by FP, FFA, and OCT. New Zealand rabbits have large eyeballs, but they have large optic disc and myelinated retinal nerve fibers in their retinas, and the growth pattern of retinal vessels were also different to the human retinas. Unlike monkeys and rabbits, the retinal vessels of SD rats and BALB/c mice were widely distributed and clear. The OCT performance of them were similar with human beings except the macular.

Conclusions: Monkey is a good model to study changes in retinal structure associated with fundus disease, rabbits are not suitable for studies on retinal vessel diseases and optic nerve diseases, and rats and mice are good models for retinal vascular diseases. These measures will help guide the choice of model and measurement technology and reduce the number of experimental animals required.

Background: Benign essential blepharospasm (BEB), aberrant facial nerve degeneration and hemifacial spasm (HFS) are all examples dystonia which, though not life-threatening, can have a significant impact on patient quality of life. The need for reliable self-rating surveys to monitor functional disability is fundamental. The Blepharospasm Disability Index (BSDI) is already a widely utilised and validated self-rating score for blepharospasm whilst the functional disability score (FDS) requires further validation. The principle aim of this study is to repeat validation of the FDS against the BSDI, which has been validated by several groups since its original description but only in patients with BEB.

Methods: A randomised blinded prospective cohort study was conducted at a single unit on 38 patients with BEB, aberrant facial nerve degeneration and HFS. Patients were blinded to complete the FDS followed by the BSDI or the BSDI followed by the FDS with a 30-minute interval.

Results: Both the FDS and BSDI were found to be reliable with high internal consistency and test-retest reliability. Both scales were also found to be moderately correlated with the Jankovic disease severity score.

Conclusions: This study is the first to use the FDS as a rating scale in patients with HFS and aberrant facial nerve degeneration. It is also the first study to formally validate the FDS as an acceptable rating scale for patients with dystonia and in particular it provides validation for its use in patients with HFS and aberrant facial nerve degeneration.

Background and Objective: Limbal stem cell deficiency (LSCD) describes the clinical condition when there is dysfunction of the corneal epithelial stem/progenitor cells and the inability to sustain the normal homeostasis of the corneal epithelium. The limbal stem cells are located in a specialized area of the eye called the palisades of Vogt (POV). There have been significant advances in the diagnosis and management of LSCD over the past decade and this review focuses on the pathophysiology of LSCD, its clinical manifestations, diagnosis, and causes.

Methods: Papers regarding LSCD were searched using PubMed to identify the current state of diagnosis and causes of LSCD published through to June 2022. 
Key Content and Findings: LSCD is clinically demonstrated by a whorl-epitheliopathy, loss of the POV, and conjunctivalization of the cornea. The diagnosis of this condition is based on clinical examination and aided by the use of impression cytology, in vivo confocal microscopy, and anterior segment optical coherence tomography (asOCT). There are many causes of LSCD, but those which are most common include chemical injuries, aniridia, contact lens wear, and Stevens-Johnson syndrome (SJS).

Conclusions: While this condition is most commonly encountered by corneal specialists, it is important that other ophthalmologists recognize the possibility of LSCD as it may arise in other co-morbid eye conditions.

The prevalence of diabetic retinopathy (DR) continues to increase in pregnant females; these individuals are also at a higher risk of disease progression. The lack of evidence regarding the safety and efficacy of current treatment options in pregnancy makes disease management particularly challenging.All pregnant women with diabetes should have a prenatal DR screening, as well as receive counseling regarding the progression and management of DR during pregnancy. Optimal blood glucose and blood pressure control should be encouraged. For patients with proliferative diabetic retinopathy (PDR) in the absence of visually significant diabetic macular edema (DME), panretinal photocoagulation (PRP) remains a safe and effective treatment option. Visually significant DME can be treated with focal laser if areas of focal leakage are identified in the macula on fluorescein angiogram, intravitreal steroids or anti-vascular endothelial growth factor (VEGF) agents, The theoretical risk of anti-VEGF agents to the fetus should be considered and the patients should be extensively counselled regarding the risks and benefits of initiating anti-VEGF therapy before initiating treatment. When the decision is made to treat with anti-VEGF agents, Ranibizumab should be the agent of choice. In conclusion, ophthalmologists should make treatment decisions in pregnant patients with DR on a case-by-case basis taking into consideration disease severity, risk of permanent threat to vision, gestational age, and patient preferences.

Background: Necrotising fasciitis (NF) is a rare but severe necrotising infection of the subcutaneous tissues. We report a case of periocular NF associated with a concurrent COVID-19 infection and explore potential mechanisms of pathogenesis of COVID-19 infection and necrotising superinfections.

Case Description: A 33-year-old previously healthy female presented with right-sided progressive periocular swelling, erythema, pain and fever, two days after sustaining a laceration to the right superolateral brow from a clenched fist. She had a concurrent COVID-19 infection, detected on nasopharyngeal polymerase chain reaction swab thirteen days prior to presentation and again at presentation. She did not have an oxygen requirement. There was a large bulbous collection of the right upper lid with fluctuance and overlying erythema, and a communicating sinus drained frank pus from the superolateral brow. Pre-operative T2-weighted MRI demonstrated fascial hyperintensity involving the pre-septal tissues and extending to the anterior temporal fossa. She was commenced on intravenous meropenem, clindamycin and vancomycin, and underwent early surgical debridement. Initial debridement demonstrated right upper lid necrosis involving the dermal and pre-septal layers, including the orbicularis, but sparing the tarsus. Streptococcus pyogenes was isolated, and she was continued on a prolonged course of intravenous antibiotic. Periocular defects were repaired with a right-sided brow adipo-fascial flap based on the supratrochlear artery, browpexy and dual full thickness skin grafts on the right upper lid and flap.

Conclusions: NF is an acute fulminant infection rarely affecting the periocular tissues. This represents a unique case of periocular NF associated with a concurrent COVID-19 infection.

Backgrounds: To assess changes in anterior segment biometry during accommodation using a swept source anterior segment optical coherence tomography (SS-OCT).

Methods: One hundred-forty participants were consecutively recruited in the current study. Each participant underwent SS-OCT scanning at 0 and ?3 diopter (D) accommodative stress after refractive compensation, and ocular parameters including anterior chamber depth (ACD), anterior and posterior lens curvature, lens thickness (LT) and lens diameter were recorded. Anterior segment length (ASL) was defined as ACD plus LT. Lens central point (LCP) was defined as ACD plus half of the LT. The accommodative response was calculated as changes in total optical power during accommodation.

Results: Compared to non-accommodative status, ACD (2.952±0.402 vs. 2.904±0.382 mm, P<0.001), anterior (10.771±1.801 vs. 10.086±1.571 mm, P<0.001) and posterior lens curvature (5.894±0.435 vs. 5.767±0.420 mm, P<0.001), lens diameter (9.829±0.338 vs. 9.695±0.358 mm, P<0.001) and LCP (4.925±0.274 vs. 4.900±0.259 mm, P=0.010) tended to decreased and LT thickened (9.829±0.338 vs. 9.695±0.358 mm, P<0.001), while ASL (6.903±0.279 vs. 6.898±0.268 mm, P=0.568) did not change significantly during accommodation. Younger age (β=0.029, 95% CI: 0.020 to 0.038, P<0.001) and larger anterior lens curvature (β=?0.071, 95% CI: ?0.138 to ?0.003, P=0.040) were associated with accommodation induced greater steeping amplitude of anterior lens curvature. The optical eye power at 0 and ?3 D accommodative stress was 62.486±2.284 and 63.274±2.290 D, respectively (P<0.001). Age was an independent factor of accommodative response (β=?0.027, 95% CI: ?0.038 to ?0.016, P<0.001).

Conclusions: During ?3 D accommodative stress, the anterior and posterior lens curvature steepened, followed by thickened LT, fronted LCP and shallowed ACD. The accommodative response of ?3 D stimulus is age-dependent.