Limbal Area Research Articles

Limbal Stem Cell Deficiency After Treatment of Ocular Surface Squamous Neoplasia.

To investigate limbal stem cell deficiency (LSCD) in patients surgically treated for ocular surface squamous neoplasia (OSSN). This retrospective case-control study investigated clinical and histological data from patients with OSSN surgically treated in a referral center. The study included 98 patients (58 male, 40 female) with a mean age of 61.1 (23-86) years. Less than 3 clock hours were involved by OSSN in 48 eyes (49.0%), 3-6 clock hours in 32 eyes (32.7%), 6-9 clock hours in 12 eyes (12.2%), and more than 9 clock hours in 6 eyes (6.1%). Limbal stem cell deficiency was identified in 36 patients (36.7%) after surgery. The severity of LSCD was mild in 17 eyes, moderate in 11, and severe in 8. The prevalence of LSCD increased significantly in groups with 6 clock hours or more of OSSN involvement (p < 0.001). The affected limbal side (superior, inferior, nasal, or temporal) had no significant association with the prevalence of LSCD (p = 0.869). Patients with recurrent OSSN had a higher LSCD prevalence (p = 0.003). The higher the tumor stage, the more likely it was to develop LSCD (p < 0.001). Patients with corneal involvement were also more likely to develop LSCD (p = 0.021). The prevalence of LSCD was raised with increasing histopathological grade (p = 0.019). Furthermore, solely the number of clock hours affected by OSSN was an independent risk factor in multivariate analyses (p < 0.001). The size and severity of OSSN and the presence of recurrent OSSN are associated with an increased likelihood of developing LSCD. Furthermore, the extent of the limbal area involved by the OSSN is identified as an independent risk factor of the development of LSCD.

EDUCATIONAL AND METHODOLOGICAL FUNDAMENTALS OF TEACHING THE TOPIC "ANATOMY OF THE SUPPORTING APPARATUS OF THE EYE"

The article is devoted to the analysis of the peculiarities of teaching the topic "Supporting apparatus of the eye" in domestic medical higher education institutions. Given the importance of studying the anatomy of the connective tissue structures of the eye socket for understanding the spread of infectious processes, we believe that in modern curricula on normal human anatomy, methodologists pay insufficient attention to their study. As a rule, these questions are only a small part of the wide variations of the topic "Accessory structures of the eye". At the same time, the peculiarities of the structure of the periosteum of the eye socket, the orbital septum, the socket of the eyeball, Whitnall's and Lockwood's ligaments, the tendinous funnel, the fascia of the rectus and oblique muscles have an extremely complex structure. Thorough knowledge of these features is a necessary condition for the development of the clinical thinking of the future doctor. The development of modern technologies for the surgical treatment of many eye diseases requires scientists and teachers to improve their knowledge of the structure of certain connective tissue structures of the eye. For example, the features of the structure and attachment of Tenon's capsule in the limbus area are the formation of an area where the approach to the fibrous membrane of the eye during surgical interventions can be carried out without damaging it. Nowadays, aesthetic surgery of the eye area is gaining particular popularity. Blepharoplasty is one of the surgical interventions most often performed in plastic surgery. Without a perfect knowledge of the structure of the orbital septum, safe performance of blepharoplasty is impossible. The surgeon needs to be oriented in the peculiarities of the structure of the orbital septum and the differences in its structure in the areas of the upper and lower eyelids. It is important to note that in the lower part of the eye socket, the space behind the orbital septum is much larger than in the upper part, it sinks into the depth of the eye socket, behind the back pole of the eye and is filled with fatty tissue, the growth of which is often an indication for surgical intervention. The structure of the upper part of the space behind the orbital septum is somewhat more complex, because it contains many vessels, nerves and connective tissue structures.

Clinical and pathologic characterization of a mouse model of graded limbal stem cell deficiency

Limbal stem cell deficiency (LSCD) is a clinically challenging eye disease caused by damage to limbal stem cells (LSCs). Currently, the international consensus classifies LSCD into three clinical stages based on the disease severity. However, no existing animal models attempt to replicate the varying degrees of LSCD observed in clinical cases. The present study demonstrates an easy-to-create, reproducible, and reliable mouse model of graded LSCD. To achieve mild, moderate, or severe LSCD, filter paper rings with a variety of central angles (90°, 180°, or 270°) are utilized to deliver alkali burns to different sizes of the limbal area (1, 2, or 3 quarters). The animal model has successfully resulted in the development of clinical signs and pathological manifestations in escalating severity that are similarly observed in the three clinical stages of LSCD. Our study thus provides new insights into distinct pathological features underlying different grades of LSCD and serves as a new tool for further exploring the disease mechanisms and developing new effective therapeutics for repairing damaged LSCs.

Recurrent conjunctival papilloma: Case report

Papilloma is a histopathological term describing specific morphology of tumors. Conjunctival papilloma is a benign growth that arises from the stratified squamous epithelium of the conjunctiva. Two cases of recurrent conjunctival papilloma who were operated and adjunctive therapy given are presented here. Both the cases had history of recurrence of conjunctival papilloma following excision. The extent of papilloma was different in both the cases. One case has minimal symptoms and lesion the inferior quadrant while the other was symptomatic in form of diminution of vision, watering, forgien body sensation, photophobia and blepharospasm with alesion extending 270 degrees of limbal area and covering whole of the cornea. The management was same in both the cases : excisional biopsy in both the eyes under local anaesthesia, intraoperative crotherapy and use of mitomycin C and post operative use of chloramphenicol and mitomycin c eye drops. Various treatment modalities have been described for management of conjunctival papilloma. These comprise conservative management, topical use of interferon alpha 2b, excisional biopsy and use of adjunctive treatment such as carbon dioxide laser, cryoablation and application of mitomycin C to prevent recurrence. This patient was managed with excisional biopsy along with adjunctive treatment in form of cryoablation and mitomycin c application to prevent recurrence.

Evaluation of the effect of intravitreal injections on corneal epithelial, scleral and limbal region changes in diabetic retinopathy by AS-OCT.

The aim of the study is to evaluate the effects of diabetic retinopathy and intravitreal injections on the corneal, limbal and scleral areas. Patients with diabetes mellitus at different diagnosis and treatment levels were compared among themselves and with the control group in terms of corneal, limbal and scleral aspects with the help of anterior segment optical coherence tomography. In addition, clinical tests such as tear break-up time, Schirmer test-I and ocular surface disease index questionnaire were applied to the patients and the difference between the groups was investigated. When the groups were examined in terms of BUT, SCH-I and OSDI, there was a statistically significant difference between control group and diabetic group(p < 0.05). In the limbal region, all measurements are higher than in patients with diabetic eye involvement. Thinning was detected in the scleral area with intravitreal injection (p < 0.05). It should be known that DM may cause undesirable changes in the limbal region, and the importance of non-invasive detection with AS-OCT should not be forgotten. Since intravitreal injections for DME cause thinning of the sclera, it can cause various complications, and it may be recommended to change the quadrant in repetitive injection applications.

Matrix-Assisted Cell Transplantation for the Treatment of Limbal Stem Cell Deficiency in a Rabbit Model.

With the development of regenerative medicine in ophthalmology, the identification of cells with high proliferative potential in the limbal area has attracted the attention of ophthalmologists and offered a new option for treatment in clinical practice. Limbal stem cell deficiency (LSCD) is an identified eye disease with a difficult and negative outcome, for which the traditional treatment is keratoplasty. This study sought to evaluate the efficacy of matrix-assisted cell transplantation consisting of in vitro-cultured autologous limbal stem cells (LSCs) and type I collagen for the treatment of LSCD in rabbits. LSCD was induced in 10 rabbits by a combination of mechanical limbectomy and alkali burns. Cells were cultured on a plate for 14 days before being transferred to a collagen-based matrix for another 7 days. Rabbits were divided into two groups as follows: the experimental group (five rabbits) received matrix-assisted cell transplantation, while the control group (five rabbits) received only conservative therapy with anti-inflammatory eye drops. During the postoperative period, all rabbits were examined using slit-lamp biomicroscopy with photo-registration and fluorescent staining, impression cytology and anterior segment optical coherence tomography (AS-OCT). Rabbits were euthanized at 30 and 120 days, and their corneas were processed for histology and immunohistochemistry. As a consequence, rabbits in the experimental group demonstrated the restoration of the corneal epithelium and transparency without epithelial defects. Moreover, goblet cells were absent in the central zone of the corneal epithelium. In conclusion, our new method of treatment enhanced the corneal surface and is an effective method of treatment for LSCD in rabbits.

Scleral Shape and Its Correlation With Corneal Topographic Parameters: A Review

Purpose. This review paper aims to summarize the outcomes of the different studies investigating the correlation between corneal and scleral profiles, outline the relationship between corneal and scleral curvatures and asymmetry, and describe the correlation between corneal astigmatism and scleral toricity in regular and irregular corneas. Material and Methods. Literature was reviewed from PubMed. A total of 48 articles were specifically selected for the current study. Results. The scleral and corneal radii are directly correlated; the greater the corneal radius, the larger the scleral radius. The cornea and sclera become gradually flatter and asym- metric as the distance from the corneal optical line increases. Similar to the central cornea, the limbal area is more likely to be spherical. The horizontal asymmetry between the nasal and temporal areas is greater than the vertical asymmetry, with the nasal region of the ocular surface being the flattest. In eyes with keratoconus, the sclera is steeper, more asym- metric, and irregular. Cone decentration predicts asymmetric sclera. Corneal and scleral toricity are more likely correlated when corneal astigmatism is greater than 2.00 D. Conclusion. Some correlations were found between corneal and scleral topography; however, performing both corneal and scleral topography are necessary when fitting contact lenses. Further investigation is needed with larger groups matched in age, refractive error, and biometry and comparing smaller or steepest eyes (i.e., Asiatic population) with larger or flatter eyes. It would also be interesting to compare such correlations in primary and secondary ectasia, investigating whether the scleral shape changes in secondary ectasia. Keywords Corneal topography, scleral profile, ocular surface asymmetry, profilometry, ocular surface radii, contact lens fitting

Novel discovery of a lymphatic bridge connecting Schlemm's canal to limbal and conjunctival lymphatic pathway

PurposeSchlemm's canal (SC) is a critical structure regulating aqueous humor (AH) drainage and intraocular pressure (IOP). It is known that in the conventional outflow pathway, AH flows from SC to episcleral veins. We recently reported a high-resolution three-dimensional (3D) imaging technology for intact eyeballs, SC and ocular surface. Using this advanced technology, we herein report the discovery of a new structure, termed lymphatic bridge, that directly connects SC to the limbal and conjunctival lymphatic pathway. Further investigation on this novel outflow pathway may provide new mechanisms and therapeutic approaches for glaucoma. MethodsAs reported previously, intact eyeballs were harvested from Prox-1-GFP (green fluorescent protein) mice and processed by a tissue clearing technique with CLARITY. Samples were immunolabeled with specific antibodies for CD31 (pan-endothelial marker) and LYVE-1 (lymphatic vessel endothelial hyaluronan receptor-1) and imaged by light-sheet fluorescent microscopy. The limbal areas were examined to locate connecting channels between SC and limbal and conjunctival lymphatic vessels. Moreover, in vivo anterior chamber dye injection was performed with Texas Red dextran for functional analysis on AH outflow. ResultsA novel lymphatic bridge structure that expressed both Prox-1 and LYVE-1 was discovered between the SC and limbal lymphatic vessels connected with conjunctival lymphatic pathway. Results from the anterior chamber dye injection also confirmed AH drainage into the conjunctival lymphatic outflow pathway. ConclusionsThis study provides the first evidence on the direct connection between SC and conjunctival lymphatic pathway. This new pathway is distinctive from the traditional episcleral vein pathway and merits further investigation.

Sublimation of Benign Conjunctival Nevi Using Plasma-Assisted Noninvasive Surgery: A Clinical Case Series.

Conjunctival nevi (CN) are common benign ocular tumors. Given their low risk of malignancy, surgical removal of nevi is primarily requested by patients. Herein, we introduce Atmospheric Low-temperature Plasma (ALTP) as a novel noninvasive method for the removal of CN. A clinical case series was conducted from 2020 to 2021 at the Vision Health Ophthalmic Center in Tehran, Iran. CN in one of the eyes of seven patients was treated. In all patients, the benignity of CN was confirmed by ocular oncologists. The white handpiece of the Plexr device, which generates plasma with the lowest output, was used to apply plasma spots on the nevi. In addition, the Ocular Surface Disease Index (OSDI) questionnaire was completed by all patients before and six months after the treatment. In all patients, the nevi outside the limbus area completely disappeared. The mean size of pre- and post-operative nevi was 3.89×11.7 and 0.54×1.69 mm, respectively. Results of the OSDI questionnaire showed significantly lower scores after the surgery in all patients. The ALTP method is a simple, cost-effective, and office-based surgery to remove CN safely and effectively.

Use of Black-and-White Digital Filters to Optimize Visualization in Cataract Surgery.

Purpose: To evaluate the effect of a black-and-white (BW) filter on the optimization of visualization at each stage of cataract surgery. Methods: Prospective, single-center, single-surgeon, consecutive case series of 40 patients undergoing cataract surgery with BW filter. Surgical images and videos were recorded with and without the BW filter at each stage of cataract surgery. Contrast measurements of surgical images and subjective analysis of video sequences were performed. Results: The surgeons assessed the BW filter to optimize the tissue visibility of capsulorhexis contours, hydrodissection fluid wave perception, the contrast of instruments through a nucleus during phaco-chop, and subincisional cortex contrast through the corneal edema. Despite the higher contrasts’ value obtained with BW filter images during nucleus removal, posterior capsular polishing and viscous removal, the surgeons subjectively reported no significant advantage of using a BW filter. Standard color images were found to be better for localizing the limbal area during incision and for nucleus sculpture to assess groove depth. Conclusions: In conclusion, we describe here the potential indications for BW filter use at particular stages in cataract surgery. A BW filter could be used, with caution, in cases of poor visualization.

Long-Term Comprehensive Management of Bilateral Limbal Stem Cell Deficiency Secondary to Severe Chemical Burn: 10 Years of Follow-Up

ABSTRACT Purpose To describe the long-term management of bilateral limbal stem cell deficiency secondary to a severe chemical burn. Methods Descriptive case report Importance This case highlights the importance of early intervention in ocular chemical burns for the preservation of tissue integrity and avoidance of perforation. We also review the use of proper ocular surface reconstructive techniques to restore the function of the limbal area, as well as the immunomodulatory strategies and follow-up needed for these interventions.

Current Advancements in Corneal Cell-Based Therapy.

Corneal epithelial stem cells (CEpSCs) mostly reside at the limbal area and are responsible for tissue homeostasis throughout life. Once complete CEpSC deficiency occurs, regenerative medicine cell-based therapy using CEpSCs or their alternatives can provide successful clinical outcomes. Due to an improved understanding of CEpSCs and mucosal epithelial stem cells, major advancements have been made over the past few decades in in vivo and ex vivo cell-based ocular surface reconstruction therapies for the treatment of severe ocular surface diseases. New therapeutic concepts and clinical strategies are emerging for the treatment of corneal endothelial dysfunction. For example, unlike corneal epithelial cells, in vivo corneal endothelial cells (CECs) stop proliferating and are arrested in the G1 phase of the cell cycle due to cell-to-cell contact inhibition and exposure to a high concentration of transforming growth factor-beta in the aqueous humor. Thus, the production of CECs with good functionality in culture has consistently been difficult. To solve this problem, Rho-associated protein kinase inhibition has taken center stage, as it not only makes the production of human CECs in culture closely mimic the functional characteristics of in vivo healthy CECs possible but also helps sustain those biological properties. Thus, cultured human CEC injection therapy is now moving to the forefront for the treatment of corneal endothelial failure. Herein, we summarize key historical discoveries in corneal cell-based regenerative medicine and illustrate the concept of corneal cell therapy for the treatment of refractory corneal epithelial and endothelial diseases.

Countering choroid prolapse in corneo scleral repair.

Background:The video shows the meticulous repair of the corneoscleral tear along with management of the choroidal prolapse.Purpose:The video demonstrates the steps to establish the anatomical integrity of the globe and tips to avoid suture bites through the choroid in a corneo-scleral tear repair.Synopsis:Identification of important landmarks helps in the establishment of anatomical integrity. Therefore, the limbal area of tear is first sutured with 10-O nylon. The extent of wound onto the sclera is checked on the other end of the tear. Second limbal suture at the opposite end of the tear is taken, followed by dividing the corneal extent of tear by rule of half and segmental suturing with 10-O nylon. Then conjunctival peritomy is done to explore the scleral extent and the uveal tissue prolapse. Blunt and atraumatic back tip of Weckel sponge is used perpendicular to the plane of the sclera to push the choroid back aiding the scleral bite. Sclera is sutured with 9-O nylon suture taking care not to include the choroidal tissue. Air injection is done to check for any wound leak. Side port is hydrated, and corneal sutures are buried. The conjunctiva is secured with fibrin glue. Anterior chamber is formed with air bubble. Povidone iodine is instilled and BCL placed.Highlights:1. Suturing the landmark areas first; 2. Exploring the extent of wound; 3. Segmental suturing of the cornea; 4. Pushing the choroid back to avoid bites through it while suturing sclera; 5. Air injection to check for wound leaks; 6. Anterior chamber formation with air at the end.Video link: https://youtu.be/e5lEyLsQR3U

CT Assessment of Vascular Density at Limbus Area after Excimer Laser Refractive Surgery in Myopic Patients

Purpose: to assess the indicators of vascular network density at limbus area in patients with myopia and myopic astigmatism before and after excimer laser refractive surgery.Material and methods. A total of 22 patients aged 18 to 37 years with myopia and myopic astigmatism of varying degrees, who previously underwent excimer laser refractive surgery, were examined. Additionally, the vascular network density at limbus area was assessed quantitatively in the preoperative and early postoperative periods using the Nidek RS-3000 AngioScan OCT device and utilizing a module for scanning the anterior segment of the eye.Results. One hour after excimer laser refraction surgery, there was a decrease in vascular network density at limbus area in all four analyzed sectors (upper, lower, temporal, nasal). One day after surgery, there was an increase in this indicator, tending to preoperative values. We were unable to identify the dependence of the degree of vascular network density on the method of corneal flap formation.Conclusion. OCT-angiography makes it possible to assess the indicators of vascular density at limbus area. The estimated indicators varied depending on the time passed after excimer laser refractive surgery.

Оценка показателей кровотока лимбальной области с помощью ангиорежима оптического когерентного томографа у пациентов с миопией и миопическим астигматизмом, перенесших эксимерлазерную коррекцию зрения

Purpose. To assess the state of blood flow in the limbal area in patients with myopia and myopic astigmatism before and after excimer laser vision correction using the Nidek RS-3000 AngioScan optical coherence tomograph. Material and methods. A total of 22 patients aged 18 to 37 with different degrees of myopia and myopic astigmatism who underwent excimer laser vision correction were examined. Additionally, the blood flow of the limbal area was studied in the preoperative and early postoperative periods using the Nidek RS-3000 AngioScan optical coherence tomograph using a module for scanning the anterior segment of the eye. Results. One hour after excimer laser vision correction, there is a decrease in blood flow of the limbal area in all 4 analyzed sectors (upper, lower, temporal, nasal), after 1 day there is an increase in blood flow indicators, tending to preoperative values. We were unable to identify the dependence of the degree of blood flow on the method of formation of the corneal flap. Conclusion. Using OCT angioregime it is possible to assess the condition of limb blood flow. In the first hour after laser vision correction blood flow parameters change in all 4 studied sectors, with a tendency to decrease, and recover to preoperative values 1 day after the surgery. Key words: optical coherent angiography of the limbal area, excimer laser vision correction, femtolaser vision correction, myopia, myopic astigmatism.

Ocular surface squamous neoplasia in Northern Thailand: a 16-year review

PurposeTo evaluate clinical characteristics, treatments, and outcomes in patients with ocular surface squamous neoplasia (OSSN) at a tertiary center in Northern Thailand.MethodsPatients diagnosed with either corneal-conjunctival intraepithelial neoplasia (CIN) or squamous cell carcinoma (SCC) from May 2000 to December 2015, were recruited. The patients’ demographics, symptoms, clinical characteristics, cytopathology, treatments, and outcomes were reviewed.ResultsOverall 171 eyes from 168 patients, 92 eyes were CIN and 79 eyes were SCC. Males were affected in 65.5%. The mean age was 58.8 ± 16.8 (29–99) years. In most cases (60.3%), the tumors were located at the limbus. The most common clinical characteristic was papilliform appearance (46.2%). Human immunodeficiency virus (HIV) infection was found in 37 (22.0%) patients with a mean age of 40.5 ± 7.7 years. The treatments and outcomes were evaluated in 136 eyes whose main initial treatment was wide excision with adjunctive cryotherapy (47.8%), followed by topical mitomycin C (30.9%). The mean follow-up time after treatment was 20.8 ± 2.2 (3–110) months and the recurrence occurred in 18 eyes (13.2%) during the follow-up period. The mean recurrence-free time (months) for CIN was significantly longer than that of SCC (81.3 ± 10.0 [95%CI 61.5 – 101.1] vs 33.2 ± 4.6 [95%CI 24.0 – 42.3], p = 0.030). SCC was the only significant risk factor that influences the recurrence of the tumors with the adjusted hazard ratio of 5.69 (p = 0.005).ConclusionOSSN in Northern Thailand usually involved a limbal area and presented as a papilliform mass. HIV infection should be suspected in young patients. CIN had better outcomes after treatments than invasive SCC.

Alterations of Ocular Surface and Tear Film in Patients with Obstructive Sleep Apnea/Hypopnea Syndrome.

PurposeObstructive sleep apnea/hypopnea syndrome (OSA) results in repeated oxygen desaturation, repeated arousals, and episodic nocturnal activation of sympathetic nervous system during sleep. Untreated OSA is strongly associated with an increase of cardio- and cerebrovascular disorders, as well as the damages of ophthalmological microstructures. However, previous literature only simply studied the association between the ophthalmic disorders and OSA. In the present study, we first investigated the alterations of ocular surface and tear film non-invasively with the innovated corneal topographer in untreated OSA patients and normal control subjects. Furthermore, we analyzed in depth whether the correlations between OSA severity and ocular surface exams exist.Participants and MethodsParticipants underwent a full-night polysomnography to determine OSA occurrence and severity. All participants subsequently received Ocular Surface Disease Index questionnaire and comprehensive ocular exams, including floppy eyelid syndrome (FES) assessment, oculus scan for tear meniscus height, non-invasive keratograph tear film breakup time (NIKBUT), and ocular surface redness, endothelial cell density, and corneal fluorescein staining.ResultsOne hundred eighty-one participants were prospectively enrolled in the study. FES was found in 11.5% of the normal control group and 60.0% of the severe OSA group (p=0.0005). There were significant differences in the first-NIKBUT (F-NIKBUT) (p < 0.0001), average-NIKBUT (A-NIKBUT) (p = 0.0007), and redness scores over the nasal bulbar (p = 0.032), temporal bulbar (p < 0.0001), nasal limbal (p = 0.014), and temporal limbal (p < 0.0001) areas among the four groups. F-NIKBUT and A-NIKBUT were significantly shorter in the moderate/severe OSA group (apnea/hypopnea index (AHI) ≥15) than in the normal/mild OSA group (AHI <15) (both p < 0.0001). The redness scores over the temporal bulbar (p < 0.0001) and temporal limbal (p < 0.0001) areas were also significantly different in these two OSA groups. Moreover, F-NIKBUT and A-NIKBUT negatively correlated with AHI. Nasal bulbar redness, temporal bulbar redness, nasal limbal redness, and temporal limbal redness positively correlated with AHI.ConclusionOSA patients had higher occurrence of FES. The NIKBUT was significantly shorter, and the temporal conjunctival redness scores over bulbar and limbal areas were higher in the moderate/severe OSA group than in the normal/mild OSA group. NIKBUT and conjunctival hyperemia significantly correlated with the severity of untreated OSA.

A spectrofluorimetric study of the limbal area in patients with primary open-angle glaucoma

Purpose: to evaluate hypoxic changes in the limbus area conjunctiva of patients with primary open-angle glaucoma (POAG) treated with prolonged instillations of prostaglandin (PG) analogs. Material and methods. A spectrofluorimetric study of the limbus zone was carried out in 202 patients aged 56–87 years with POAG in the developed and advanced stages, divided into 2 groups. Group 1 consisted of patients aged 69.4 ± 10.3 years who received beta-blockers (BB) and carbonic anhydrase inhibitors (ICA) for 5–10 months; of these, 39 (30.2 %) had a developed stage of POAG and 90 (69.7 %) had advanced POAG. Group 2, aged 72.3 ± 9.4, received PG analogs, in addition to BB and ICA, for 5–10 months. In this group, 21 (28.7 %) patients had developed POAG and 52 (71.23 %) had advanced POAG. Results. The patients who received PG instillations showed a significantly higher ratio of fluorescence intensity in the wavelength range of 410/520 nm NADH/FAD (0.352 ± 0.043) than those receiving no such therapy (0.319 ± 0.047), which can be interpreted as a hypoxic state of the limbus area. Conclusion. Spectrofluorimetric testing of POAG patients taking PG analogs can be useful for detecting ischemia in the limbus area, because this category of patients are very likely to form cicatricial changes in the area of the filtration cushion in the early postoperative period after antiglaucomatous interventions.

Cell Morphology as an In Vivo Parameter for the Diagnosis of Limbal Stem Cell Deficiency.

The aim of this study was to investigate basal epithelial cell morphology (CM) in the central cornea and limbal areas of eyes with limbal stem cell deficiency (LSCD). This was a prospective, cross-sectional comparative study. We developed a CM scoring system based on basal epithelial cell phenotypes graded from 0 (normal) to 3 (severe morphologic alterations); this system was evaluated by 2 independent masked observers. The CM score was compared with the LSCD clinical score, mean best-corrected visual acuity, and in vivo laser scanning confocal microscopy parameters used to stage LSCD (ie, basal epithelial cell density, basal epithelial thickness, and subbasal corneal nerve fiber length density). One hundred sixty-eight eyes with LSCD and 63 normal eyes were included. Compared with the control group, the LSCD group had significantly higher mean (±SD) CM scores in the central cornea (1.8 ± 0.7 vs. 0.5 ± 0.4, respectively; P = 0.01) and limbal areas (1.6 ± 0.2 vs. 1.3 ± 0.0, respectively; P < 0.05). The mean CM score in the central cornea was positively correlated with the clinical score ( P < 0.01, r = 0.66) and negatively correlated with the best-corrected visual acuity ( P < 0.01, r = 0.42). The CM scores were positively correlated with all other in vivo laser scanning confocal microscopy parameters in the central cornea and limbal areas (all P < 0.001). Basal epithelial CM is altered in the central cornea and limbus of eyes with LSCD and thus can be used to stage the clinical severity of the disease.

Open-Source Automatic Biomarker Measurement on Slit-Lamp Photography to Estimate Visual Acuity in Microbial Keratitis.

PurposeTo assess clinical applicability of automatic image analysis in microbial keratitis (MK) by evaluating the relationship between biomarker measurements on slit-lamp photography (SLP) and best-corrected visual acuity (BCVA).MethodsSeventy-six patients with MK with SLP images and same-day logarithm of the minimum angle of resolution (logMAR) BCVA were evaluated. MK biomarkers (stromal infiltrate, white blood cell infiltration, corneal edema, hypopyon, epithelial defect) were segmented manually by ophthalmologists and automatically by a novel, open-source, deep learning–based segmentation algorithm. Five measurements (presence, maximum width, total area, proportion of the corneal limbus area affected, centrality) were calculated. Correlations between the measurements and BCVA were calculated. An automatic regression model estimated BCVA from the measurements. Differences in performance between using manual and automatic measurements were evaluated using William's test (for correlation) and the paired-sample t-test (for absolute error).ResultsMeasurements had high correlations of 0.86 (manual) and 0.84 (automatic) with true BCVA. Estimated BCVA had average (mean ± SD) absolute errors of 0.39 ± 0.27 logMAR (manual, median: 0.30) and 0.35 ± 0.28 logMAR (automatic, median: 0.30) and high correlations of 0.76 (manual) and 0.80 (automatic) with true BCVA. Differences between using manual and automatic measurements were not statistically significant for correlations of measurements with true BCVA (P = .66), absolute errors of estimated BCVA (P = .15), or correlations of estimated BCVA with true BCVA (P = .60).ConclusionsThe proposed algorithm measured MK biomarkers as accurately as ophthalmologists. Measurements were highly correlated with and estimative of visual acuity.Translational RelevanceThis study demonstrates the potential of developing fully automatic objective and standardized strategies to aid ophthalmologists in the clinical assessment of MK.