Background and Objective: Nearly 30 years have passed since limbal stem cell deficiency (LSCD) was first identified by pioneers and given clinical attention. LSCD remains a difficult disease to treat. It can potentially lead to blinding. At present, understanding of limbal stem cells (LSCs) has deepened and various treatment options for LSCD have been devised. The objective of this review is to summarize basic knowledge of LSCD and current treatment strategies.Methods: PubMed search was performed to find studies published in English on LSCs and LSCD including original reports and reviews. Literatures published from 1989 to 2022 were reviewed.
Key Content and Findings: LSCs are enigmatic stem cells for which no specific marker has been discovered yet. Although LSCD is not difficult to diagnose, it is still challenging to treat. An important advancement in the treatment of LSCD is the provision of guidelines for selecting systematic surgical treatment according to the patient’s condition. It is also encouraging that stem cell technologies are being actively investigated for their potential usefulness in the treatment of LSCD.Conclusions: Although various treatment options for LSCD have been developed, it should be kept in mind that the best chance of treatment for LSCD is in the early stage of the disease. Every effort should be made to preserve as many LSCs as possible in the early treatment of LSCD.
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.
Contrast is the differential luminance between one object and another. Contrast sensitivity (CS) quantifies the ability to detect this difference: estimating contrast threshold provides information about the quality of vision and helps diagnose and monitor eye diseases. High contrast visual acuity assessment is traditionally performed in the eye care practice, whereas the estimate of the discrimination of low contrast targets, an important complementary task for the perception of details, is far less employed. An example is driving when the contrast between vehicles, obstacles, pedestrians, and the background is reduced by fog. Many conditions can selectively degrade CS, while visual acuity remains intact. In addition to spatial CS, “temporal” CS is defined as the ability to discriminate luminance differences in the temporal domain, i.e., to discriminate information that reaches the visual cortex as a function of time. Likewise, temporal sensitivity of the visual system can be investigated in terms of critical fusion frequency (CFF), an indicator of the integrity of the magnocellular system that is responsible for the perception of transient stimulations. As a matter of fact, temporal resolution can be abnormal in neuro-ophthalmological clinical conditions. This paper aims at considering CS and its application to the clinical practice.
Conjunctival flaps have previously proven to be effective in preserving the globe for individuals with severe ocular surface disease. Infectious keratitis, neurotrophic keratitis, nontraumatic corneal melts, descemetoceles, perforations, and corneal burns are all indications for this procedure. The flaps promote nutrition, metabolism, structure, and vascularity, as well as reduce pain, irritation, inflammation, and infection. Furthermore, patients avoid the emotional and psychological repercussions of enucleation or evisceration, while requiring fewer postoperative medications and office visits. Currently, fewer flaps are performed due to the emergence of additional therapeutic techniques, such as serum tears, bandage lenses, corneal grafting, Oxervate, amniotic membrane, and umbilical cord grafting. However, despite newer conservative medical methods, conjunctival flaps have been demonstrated to be useful and advantageous. Moreover, future technologies and approaches for globe preservation and sight restoration after prior conjunctival flaps are anticipated. Herein, we review the history, advantages, and disadvantages of various surgical techniques: Gundersen’s bipedicle flap, partial limbal advancement flap, selective pedunculated conjunctival flap with or without Tenon’s capsule, and Mekonnen’s modified inferior palpebral-bulbar conjunctival flap. The surgical pearls and recommendations offered by the innovators are also reviewed, including restrictions and potential complications. Procedures for visual rehabilitation in selective cases after conjunctival flap are reviewed as well.
Perception is the ability to see, hear, or become aware of external stimuli through the senses. Visual stimuli are electromagnetic waves that interact with the eye and elicit a sensation. Sensations, indeed, imply the detection, resolution, and recognition of objects and images, and their accuracy depends on the integrity of the visual system. In clinical practice, evaluating the integrity of the visual system relies greatly on the assessment of visual acuity, that is to say on the capacity to identify a signal. Visual acuity, indeed, is of utmost importance for diagnosing and monitoring ophthalmological diseases. Visual acuity is a function that detects the presence of a stimulation (a signal) and resolves its detail(s). This is the case of a symbol like “E”: the stimulus is detected, then it is resolved as three horizontal bars and a vertical bar. In fact, within the clinical setting visual acuity is usually measured with alphanumeric symbols and is a three-step process that involves not only detection and resolution, but, due to the semantic content of letters and numbers, their recognition. Along with subjective (psychophysical) procedures, objective methods that do not require the active participation of the observer have been proposed to estimate visual acuity in non-collaborating subjects, malingerers, or toddlers. This paper aims to explain the psychophysical rationale underlying the measurement of visual acuity and revise the most common procedures used for its assessment.
Background: Femtosecond laser astigmatic keratotomy (FSAK) and toric intraocular lens (IOL) implantation have been studied individually for comparison to treat astigmatism at cataract surgery. We report a case of surgically induced high corneal astigmatism by laser thermal keratoplasty (LTK) in a patient with cataract who was successfully treated with simultaneous combination of FSAK and toric IOL implantation with femtosecond laser-assisted cataract surgery (FLACS). This is the first report of both procedures combined simultaneously, with or without history of LTK.
Case Description: A 68-year-old male presented with a history of LTK with two enhancements each eye in 2004, with subsequent surgically induced high corneal astigmatism, and with age-related nuclear cataract of both eyes. IOL master demonstrated +7.71 diopters of astigmatism at 163 degree right eye and +3.29 diopters of astigmatism at 4 degree left eye. After extensive discussion of the risks and benefits, the patient agreed to undergo FLACS with FSAK with two 61 degrees of relaxation incisions (RIs) and toric IOL (Alcon SN6AT9) right eye; FLACS with toric IOL (Alcon SN6AT7) alone left eye. At 2-year follow-up, uncorrected visual acuity was 20/30 right eye, 20/25 left eye. His best corrected visual acuity was 20/25 (+0.25 +1.00 axis 21) right eye and 20/20 (plano +0.25 axis 90) left eye; his best corrected near visual acuity was J1+ with add +2.50 diopters right eye and left eye.
Conclusions: Patients with age-related cataract and LTK induced high corneal astigmatism can hardly be sufficiently treated with FSAK or toric IOL alone at the time of cataract surgery. An effective way is to combine large FSAK and toric IOL of the highest cylindrical power of T9, in our case, simultaneously, which can achieve an excellent long term visual outcome.
