Reevaluation of corneal complications after closed vitrectomy

Persistent Corneal Epithelial Defect Following Pars Plana Vitrectomy: A Narrative Review

PURPOSE

Persistent corneal epithelial defects (PCEDs) following pars plana vitrectomy (PPV) represent a significant clinical challenge, potentially leading to corneal scarring, vision loss, and other severe complications. This review aims to summarize the prevalence, associated risk factors, and management strategies for PCEDs in the context of PPV, providing evidence-based guidance for clinicians.

METHODS

A comprehensive systematic review was conducted using PubMed and Embase databases, identifying English-language studies addressing PCEDs after PPV.

RESULTS

The prevalence of PCEDs post-PPV varied widely, from 0% to 78.37%, influenced by intrinsic factors such as diabetes mellitus, which impairs corneal nerve function and healing, and extrinsic factors like intraoperative tamponade with C3F8. Management strategies ranged from conservative options like bandage contact lenses to advanced treatments like topical insulin.

CONCLUSION

PCEDs after PPV are multifactorial and demand individualized management. Advanced therapies, particularly serum-based treatments, and topical insulin, show promising outcomes. Further prospective research is warranted to refine these treatments.

Diverse calcium signaling profiles regulate migratory behavior in avascular wound healing and aberrant signal hierarchy occurs early in diabetes

In avascular wound repair, calcium signaling events are the predominant mechanism cells use to transduce information about stressors in the environment into an effective and coordinated migratory response. Live cell imaging and computational analysis of corneal epithelial wound healing revealed that signal initiation and propagation at the wound edge are highly ordered, with groups of cells engaging in cyclical patterns of initiation and propagation. The cells in these groups exhibit a diverse range of signaling behavior, and dominant "conductor cells" drive activity in groups of lower-signaling neighbors. Ex vivo model systems reveal that conductor cells are present in wing cell layers of the corneal epithelium and that signaling propagates both within and between wing and basal layers. There are significant aberrations in conductor phenotype and interlayer propagation in type II diabetic murine models, indicating that signal hierarchy breakdown is an early indicator of disease. In vitro models reveal that signaling profile diversity and conductor cell phenotype is eliminated with P2X7 inhibition and is altered in Pannexin-1 or P2Y2 but not Connexin-43 inhibition. Conductor cells express significantly less P2X7 than their lower-signaling neighbors and exhibit significantly less migratory behavior after injury. Together, our results show that the postinjury calcium signaling cascade exhibits significantly more ordered and hierarchical behavior than previously thought, that proteins previously shown to be essential for regulating motility are also essential for determining signaling phenotype, and that loss of signal hierarchy integrity is an early indicator of disease state. NEW & NOTEWORTHY Calcium signaling in corneal epithelial cells after injury is highly ordered, with groups of cells engaged in cyclical patterns of event initiation and propagation driven by high-signaling cells. Signaling behavior is determined by P2X7, Pannexin-1, and P2Y2 and influences migratory behavior. Signal hierarchy is observed in healthy ex vivo models after injury and becomes aberrant in diabetes. This represents a paradigm shift, as signaling was thought to be random and determined by factors in the environment.

GIANT INTRAOPERATIVE CORNEAL BULLA MANAGED WITH BANDAGE LENS TECHNIQUE DURING VITRECTOMY SURGERY

PURPOSE

To report a case of giant intraoperative corneal bulla formation in a patient with a history of recent phacoemulsification with clear corneal incision that was managed with a bandage contact lens intraoperatively.

METHODS

Retrospective case report with anterior segment optical coherence tomography.

RESULTS

A 77-year-old woman with a history of recent complicated cataract surgery with retained lens fragments underwent pars plana vitrectomy and scleral-fixated intraocular lens placement. During pars plana vitrectomy, a large corneal bulla formed at the site of the main corneal incision, confirmed with anterior segment optical coherence tomography. A bandage contact lens with viscoelastic was used to overcome visualization challenges and safely proceed with the surgery.

CONCLUSION

This is the first report of corneal bullae formation during pars plana vitrectomy that is confirmed by anterior segment optical coherence tomography and successfully managed with a bandage contact lens intraoperatively.

Complications in Retinal Surgery: A Review of Corneal Changes Following Vitreoretinal Procedures

Purpose:

The purpose of this article is to discuss the early- and late-onset corneal complications that can occur following vitreoretinal surgery.

Methods:

A systematic review of the literature was conducted using PubMed and Google Scholar databases. Articles detailing the clinical findings and the associations between surgical techniques, irrigating solutions, and microsurgical instruments used for vitreoretinal surgery and postoperative corneal complications were included in this review.

Results:

Vitreoretinal surgery can be associated with corneal complications such as persistent corneal epithelial defects, neurotrophic keratopathy, band keratopathy, ocular surface disruption, and endothelial cell damage. Risk factors for the development of cornea complications after posterior segment surgery include history of uncontrolled diabetes mellitus, aphakia or pseudophakia, disrupted anterior lens capsule integrity, use of irrigating solutions without appropriate buffers, use of contact viewing lenses intraoperatively, intraocular gases or silicone oil after vitrectomy, and prolonged duration of surgery.

Conclusions:

Corneal complications secondary to vitreoretinal surgery are multifactorial, but more commonly arise in diabetic patients, those with preexisting ocular comorbidities, and under certain surgical-related conditions. Special pre-, peri-, and postoperative considerations, with a focus on early identification and management of risk factors, are required to help decrease the incidence of corneal complications.

Effects of the Topical Use of the Natural Antioxidant Alpha-Lipoic Acid on the Ocular Surface of Diabetic Patients with Dry Eye Symptoms

PURPOSE

The purpose of this study is to investigate the effects of the treatment with eye-drops based on a combination of antioxidant and mucomimetic molecules, namely 0.1% alpha-lipoic acid (ALA) and 0.3% hydroxy-propyl-methylcellulose (HPMC) on the ocular surface of diabetic patients with dry eye symptoms.

METHODS

Seventy patients, 42 M and 28 F, aged from 50 to79 years (mean 62.1 ± 10.5), affected by type II diabetes mellitus, were enrolled and divided in two groups treated for 2 months as follows: Group 1 (35 patients), received topical ALA/HPMC three times a day, Group 2 (35 patients) received topical HPMC (0.3%) alone, three times a day. The main outcome measures were: Ocular Surface Disease Index (OSDI), tear film break-up time (TBUT), corneal fluorescein staining, Schirmer I test, corneal sensitivity. An examination of tear film morphology with confocal microscopy was carried out in a subset of patients of each group at baseline and after two months. Statistical analysis was performed with t-test for the parametric data and Mann-Whitney U-test or chi-squared test for the nonparametric data.

RESULTS

Both treatments resulted in significant improvements of BUT, OSDI and tear film morphology, although the improvements observed in group 1 showed a higher trend than what observed for group 2. Moreover, only in group 1 a significant improvement was visible for corneal staining, and no significant improvements were observed in any group for Schirmer I and sensitivity.

CONCLUSIONS

These results confirmed the efficacy of HPMC in the treatment of diabetic dry eye and indicated that the addition of a strong self-regenerating antioxidant like ALA may give a distinctive advantage for the healing of corneal defects (as evidenced by corneal staining), beside improving HPMC efficacy on three other parameters (BUT, OSDI score, tear morphology). Therefore, the addition of a strong antioxidant like ALA can be helpful in preventing or treating ocular surface defects in diabetic patients, in which the oxidative damage is predominant.

Corneal epithelial defects following vitreoretinal surgery: incidence and outcomes from the DISCOVER study

AIM

To investigate the incidence, risk factors, clinical course, and outcomes of corneal epithelial defects (CED) following vitreoretinal surgery in a prospective study setting.

METHODS

This was a post-hoc analysis of all participants in DISCOVER intraoperative optical coherence tomography study. Subjects with CED 1d after surgery without intraoperative corneal debridement was defined as the postoperative CED group. Subjects who underwent intraoperative debridement were defined as intraoperative debridement group. Eyes were matched 2:1 with controls (eyes without postoperative CED) for comparative assessment. The primary outcomes were the incidence of CED on postoperative day one and the incidence of required intraoperative debridement. Secondary outcomes included time to defect closure, delayed healing (>2wk), visual acuity (VA) and presence of scarring at one year and cornea consult.

RESULTS

This study included 856 eyes that underwent vitreoretinal surgery. Intraoperative corneal debridement was performed to 61 (7.1%) subjects and postoperative CED developed spontaneously in 94 (11.0%) subjects. Significant factors associated with postoperative CED included prolonged surgical duration (P=0.003), diabetes mellitus (P=0.04), postoperative ocular hypotension (P<0.001). Prolonged surgical duration was associated with intraoperative debridement. Delayed defect closure time (>2wk) was associated with corneal scar formation at the end of the 1y in all epithelial defect subjects (P<0.001). The overall rate of corneal scarring for all eyes undergoing vitrectomy was 1.8%.

CONCLUSION

Prolonged duration of surgery is the strongest factor associated with both intraoperative debridement and spontaneous postoperative CED. Delayed defect closure is associated with a greater risk of corneal scarring at one year. The overall rate of corneal scarring following vitrectomy is low at <2%.

Topical Umbilical Cord Serum for Corneal Epithelial Defects after Diabetic Vitrectomy

PURPOSE

To evaluate the role of topical umbilical cord serum (TUCS) therapy in treating corneal epithelial defects (CEDs) after diabetic vitrectomy.

METHODS

In this double-masked, randomized clinical trial, we included 80 eyes of 80 patients who were candidates for vitrectomy due to proliferative diabetic retinopathy complications. In cases of corneal edema obscuring the fundus view during surgery, the corneal epithelium was removed using a 6-mm trephine and a blade no.15. The day after the surgery, patients were randomly divided into two groups: (1) the TUCS group that received 20% TUCS six times/day in addition to the conventional treatment of CED and (2) the control group, which was prescribed artificial tears as placebo in addition to the conventional treatment of CED. The rate of healing of CEDs was measured via two maximum linear dimensions perpendicular to each other at the start of therapy and on postoperative days 1-5, 7, and 12.

RESULTS

Of 80 eyes, 40 were assigned to each treatment group. The mean times to complete CED healing were 2.4 ± 0.7 and 3.8 ± 2.1 days in the TUCS and control groups, respectively (P < 0.001). Persistent CED occurred in two eyes in the control group but in no eyes in the TUCS group.

CONCLUSION

TUCS therapy may be safe and effective in healing CEDs after vitrectomy in patients with diabetes.

EFFECT OF LUBRICANTS ON CORNEAL THICKNESS AFTER VITRECTOMY

PURPOSE

This study examines the impact of corneal surface lubricants used during pars plana vitrectomy on corneal edema.

METHODS

This prospective, observational, clinical study occurred at an academic institution. Participants were individuals aged 18 years and older who had already consented to undergo pars plana vitrectomy, without pre-existing corneal pathology. A corneal lubricant was chosen by the surgeon. Corneal thickness was measured preoperatively and postoperatively using pachymetry and anterior segment optical coherence tomography (AS-OCT). Main outcome measure was change in corneal thickness as measured by pachymetry.

RESULTS

Forty-one patients completed the study protocol. The 23 subjects in the SHCS group had a significantly smaller increase in corneal thickness as measured by pachymetry compared with the 18 subjects in the HPMC group (29.9 μm vs. 58.1 μm, P value 0.02). When measured by anterior segment optical coherence tomography, the SHCS group had a smaller increase in corneal thickness compared with the HPMC group (0.04 mm vs. 0.06 mm, P value 0.09) but did not reach significance.

CONCLUSION

SHCS is associated with reduced postoperative increase in corneal pachymetry as compared to HPMC.

Schirmer test changes after 20 gauge and 23 gauge pars plana vitrectomy

Objective: To evaluate the short-term changes in Schirmer I test (ST) after pars plana vitrectomy and to compare the results between 23 gauge and 20 gauge vitrectomy surgeries.

Methods: 42 patients who underwent pars plana vitrectomy for posterior segment diseases were included in this prospective, non-randomized, comparative study. The choice of sclerotomy gauge was at the surgeons’ discretion. ST values were recorded before and at 1 and 3 months after vitrectomy.

Results: 20 patients in 23 gauge and 22 patients in 20-gauge group with a mean age of 59.9 ± 13.5 years were included. The mean preoperative ST values decreased significantly in both groups at 1 and 3 months after surgery (all P < 0.01). The ST values in the fellow eyes were the same, at baseline and during the follow up (P > 0.05). At 3 months visit, 15 eyes (35.7%) had abnormal ST measurements. There was no statistically significant difference in the changes in the ST measurements between the two groups at one month (P = 0.7), however, 3 months after surgery, the mean decrease in the ST measurements was significantly higher in the 20 gauge group (P = 0.03). At 3 months, 4 eyes in the 23 gauge group (20%) and 11 eyes in the 20 gauge group (50%) had abnormal ST measurements (P = 0.05).

Conclusions: Although both 20 and 23-gauge vitrectomy decrease the ST measurements postoperatively, the value is less affected by the 23-gauge vitrectomy.

TFOS DEWS II iatrogenic report

Dry eye can be caused by a variety of iatrogenic interventions. The increasing number of patients looking for eye care or cosmetic procedures involving the eyes, together with a better understanding of the pathophysiological mechanisms of dry eye disease (DED), have led to the need for a specific report about iatrogenic dry eye within the TFOS DEWS II. Topical medications can cause DED due to their allergic, toxic and immuno-inflammatory effects on the ocular surface. Preservatives, such as benzalkonium chloride, may further aggravate DED. A variety of systemic drugs can also induce DED secondary to multiple mechanisms. Moreover, the use of contact lens induces or is associated with DED. However, one of the most emblematic situations is DED caused by surgical procedures such as corneal refractive surgery as in laser-assisted in situ keratomileusis (LASIK) and keratoplasty due to mechanisms intrinsic to the procedure (i.e. corneal nerve cutting) or even by the use of postoperative topical drugs. Cataract surgery, lid surgeries, botulinum toxin application and cosmetic procedures are also considered risk factors to iatrogenic DED, which can cause patient dissatisfaction, visual disturbance and poor surgical outcomes. This report also presents future directions to address iatrogenic DED, including the need for more in-depth epidemiological studies about the risk factors, development of less toxic medications and preservatives, as well as new techniques for less invasive eye surgeries. Novel research into detection of early dry eye prior to surgeries, efforts to establish appropriate therapeutics and a greater attempt to regulate and oversee medications, preservatives and procedures should be considered.

Diabetic complications in the cornea

Diabetic corneal alterations, such as delayed epithelial wound healing, edema, recurrent erosions, neuropathy/loss of sensitivity, and tear film changes are frequent but underdiagnosed complications of both type 1 (insulin-dependent) and type 2 (non-insulin-dependent) diabetes mellitus. The disease affects corneal epithelium, corneal nerves, tear film, and to a lesser extent, endothelium, and also conjunctiva. These abnormalities may appear or become exacerbated following trauma, as well as various surgeries including retinal, cataract or refractive. The focus of the review is on mechanisms of diabetic corneal abnormalities, available animal, tissue and organ culture models, and emerging treatments. Changes of basement membrane structure and wound healing rates, the role of various proteinases, advanced glycation end products (AGEs), abnormal growth and motility factors (including opioid, epidermal, and hepatocyte growth factors) are analyzed. Experimental therapeutics under development, including topical naltrexone, insulin, inhibitors of aldose reductase, and AGEs, as well as emerging gene and cell therapies are discussed in detail.

Corneal epithelial defect after pars plana vitrectomy

AIM:

This study aims to study the incidence of corneal epithelial defect (CED) after pars plana vitrectomy (PPV) and associated patient-related risk factors. The incidence of other immediate postoperative complications was also in the scope of this study.

DESIGN:

Retrospective descriptive case series study.

METHODS:

Review of electronic medical records of all patients who underwent PPV alone or combined with cataract surgery and/or scleral buckle in a tertiary hospital by one retinal surgeon. All demographic data, surgery notes, and immediate postoperative findings were obtained for all patients.

RESULTS:

The cohort of the included cases was composed of a total of 168 procedures that were performed in 121 eyes of 106 patients over 5 years. CEDs occurred in 19 eyes (15.7%) of 19 patients (17.9%). Males were affected more than females (90% vs. 10%). Patients with postoperative CED were found to have longer duration of surgery when compared to patients without postoperative CED (P = 0.0038). All cases of CED had a complete resolution of the defects after supportive therapy. Immediate intraocular hypertension (IOH) was found in 30 eyes (24.8%). IOH was controlled in all cases with medical therapy only. Post-PPV immediate complications, other than CED and IOH, occurred in 10.7% of the eyes. These included vitreous hemorrhage, choroidal detachment, corneal edema, anterior chamber fibrin, and hyphema.

CONCLUSION:

Development of CED is not uncommon after PPV. This complication is more common in males and may be related to prolonged duration of surgery. It also develops more in older patients. CED after PPV can be managed with conservative treatment with good outcome.

PERSISTENT CORNEAL EPITHELIAL DEFECT AFTER PARS PLANA VITRECTOMY

PURPOSE

To investigate the incidence, risk factors, and clinical course of persistent corneal epithelial defects (PCED) after pars plana vitrectomy (PPV).

METHODS

The charts of 426 consecutive patients (511 eyes) who received PPV from January 2008 to December 2011 were reviewed. Corneal complications were defined as the presence of corneal epithelial defects, corneal edema, or superficial punctate keratopathy at least 1 week after vitrectomy. The PCED was defined as corneal epithelial defects lasting longer than 2 weeks after vitrectomy despite conventional treatment. The demographic, preoperative, intraoperative, and postoperative data were compared between PCED and non-PCED corneal complication groups to evaluate the risk factors and clinical outcomes.

RESULTS

Postoperative corneal complications developed in 103 of 460 (22.4%) eyes. Diabetes was associated with postoperative corneal epithelial defects (P = 0.021) and superficial punctate keratopathy (P = 0.022) but not corneal edema (P = 0.925). Among 103 eyes with corneal complications, 21 eyes developed PCED. The eyes with PCED had poor final visual acuity, with 23.8% (5/21) of the eyes in the PCED group having visual acuity of 20/200 or better compared with 51.2% (42/82) of the eyes in the non-PCED group (P = 0.024). Logistic regression analysis demonstrated that diabetes mellitus (P = 0.025), use of perfluoropropane (P = 0.001), and assistance of a first-year resident (P = 0.029) were statistically significant risk factors for PCED after PPV. There was also a high incidence of geographic herpes simplex virus epithelial keratitis among recalcitrant PCEDs lasting longer than 4 weeks (36%, 4/11 eyes).

CONCLUSION

The overall incidence of PCED after PPV was 4.8%. Diabetes mellitus, intravitreal tamponade with perfluoropropane, and assistance of a first-year resident were risk factors for PCED after PPV. Persistent corneal epithelial defects after PPV were correlated with poor postoperative visual outcomes. Early and aggressive management is necessary for patients presenting with corneal epithelial defects after vitrectomy to prevent poor outcomes.

Ocular Complications of Diabetes and Therapeutic Approaches

Diabetes mellitus (DM) is a metabolic disease defined by elevated blood glucose (BG). DM is a global epidemic and the prevalence is anticipated to continue to increase. The ocular complications of DM negatively impact the quality of life and carry an extremely high economic burden. While systemic control of BG can slow the ocular complications they cannot stop them, especially if clinical symptoms are already present. With the advances in biodegradable polymers, implantable ocular devices can slowly release medication to stop, and in some cases reverse, diabetic complications in the eye. In this review we discuss the ocular complications associated with DM, the treatments available with a focus on localized treatments, and what promising treatments are on the horizon.

Dry eye disease in type 2 diabetes mellitus; comparison of the tear osmolarity test with other common diagnostic tests: a diagnostic accuracy study using STARD standard

BACKGROUND

To determine the diagnostic performance of tear osmolarity in diagnosis of dry eye disease by using tear lab osmolarity system in people with type 2 diabetes, and to compare it with common diagnostic tests already available in clinical practice.

METHODS

Two hundreds forty three people with type 2 diabetes were included. Tear osmolarity was measured with the tear osmolarity system. The 308 mOsm/L cutoff was used to diagnose dry eye disease. The following tests were also performed: Ocular Surface Disease Index (OSDI) questionnaire, Tear Film Break up Time (TFBUT), Schirmer I test, Rose Bengal and Fluorescein staining. The results of these tests were compared to the tear osmolarity measurement.

RESULTS

The prevalence of dry eye disease detected by the tear osmolarity test was 27.7%. It was as follows for the other common diagnostic tests: OSDI (17.7%), Schirmer I test (33%), TFBUT (41%), Rose Bengal (11%), and Fluorescein staining (4%). Fluorescein staining had the highest specificity (97%). With the cutoff score >12, the positive likelihood ratio for the OSDI questionnaire was the highest (1.78). The sensitivity was poor for all common diagnostic tests. ROC curve analysis could not determine optimal cut offs for the common diagnostic tests.

CONCLUSIONS

The available common diagnostic tests underestimate the presence of dry eye disease in people with type 2 diabetes. Moreover, they could not discriminate tear hyperosmolarity from normal. Tear osmolarity could be considered as the best single test for detection of dry eye disease in people with type2 diabetes.

Ocular complications of diabetes mellitus

Diabetes mellitus (DM) is a important health problem that induces ernestful complications and it causes significant morbidity owing to specific microvascular complications such as, retinopathy, nephropathy and neuropathy, and macrovascular complications such as, ischaemic heart disease, and peripheral vasculopathy. It can affect children, young people and adults and is becoming more common. Ocular complications associated with DM are progressive and rapidly becoming the world's most significant cause of morbidity and are preventable with early detection and timely treatment. This review provides an overview of five main ocular complications associated with DM, diabetic retinopathy and papillopathy, cataract, glaucoma, and ocular surface diseases.

Description of the sphingolipid content and subspecies in the diabetic cornea

PURPOSE

Diabetes mellitus (DM) is characterized by high blood sugar levels over a prolonged period. Long term complications include but not limited heart disease, stroke, kidney failure, and ocular damage. An estimated 382 million people are diagnosed with Type 2 DM accounting for 90% of the cases. Common corneal dysfunctions associated with DM result in impaired vision due to decreased wound healing, corneal edema, and altered epithelial basement membrane. Lipids play a fundamental role in tissue metabolism and disease states. We attempt to determine the role of sphingolipids (SPL) in human Type I and Type II diabetic corneas.

MATERIALS AND METHODS

Cadaver corneas from healthy (non-diabetic/no ocular trauma), Type I (T1DM), and Type II diabetic (T2DM) donors were obtained and processed for lipidomics using LC-MS/MS.

RESULTS

Our data show significant differences in the SPL composition between control, T1DM and T2DM corneas. Both T1DM and T2DM showed a 10-folddownregulation of sphingomyelin(SM), 5-fold up regulation of Ceramides (Cer) and 2-fold upregulation of monohexosylceramides (MHC). Differences were also seen in total amounts of SPL where Cer was increased by approximately 3 fold in both T1DM and T2DM where SM decreased by 50% in both T1DM and T2DM when compared to healthy controls. No differences were seen in MHC amounts.

CONCLUSIONS

Overall, our data indicate major differences in SPL distribution in human diabetic corneas. Information on the sphingolipids role in cornea, corneal cell physiology, and diseases are very limitedwhich highlights the importance of these findings.

Changes in corneal sensation following 20 and 23 G vitrectomy in diabetic and non-diabetic patients

PURPOSE

To evaluate the changes in corneal sensation (CS) following two different port sizes vitrectomy in diabetic and non-diabetic patients.

PATIENTS AND METHODS

Patients prepared for pars plana vitrectomy were randomly assigned to four groups: diabetics to either 20 G or 23 G and non-diabetics to either 20 G or 23 G vitrectomy systems. CS was measured using the Cochet-Bonnet aesthesiometer at baseline preoperatively, and at 1 day, 1 week, and 1 month postoperative.

RESULTS

A total of 40 eyes of 40 patients were included in this study; 20 patients (20 eyes) in each of the 20-G and 23-G groups. The mean age was 55.51±10 years and male/female ratio was 2:3. There were no significant difference between CS at baseline, and at 1 day, 1 week, and 1 month between both the 20-G and 23-G groups. There were significant drops in CSs at 1 day and 1 week for both groups (20 G and 23 G) with incomplete recovery for the 20-G group and complete recovery for the 23-G group. Comparing the two diabetic subgroups (20 G and 23 G) and two non-diabetic subgroups (20 G and 23 G), there were no significant differences in CS between subgroups. Diabetics' eyes had lower CSs throughout the study period in the 20-G and 23-G groups, which was significant at day1 and week 1 postoperatively.

CONCLUSION

The vitrectomy procedure showed reduction in CS in the postoperative period with minimal nonsignificant difference between 20 G and 23 G systems. However, diabetics' eyes showed compromised CS preoperatively and a further significant reduction for 1 month postoperatively compared with non-diabetics.

Diabetic keratopathy and treatment by modulation of the opioid growth factor (OGF)-OGF receptor (OGFr) axis with naltrexone: a review

The opioid growth factor (OGF)-OGF receptors (OGFr) axis plays an important role in the homeostasis and re-epithelialization of the mammalian cornea. This tonically active growth regulatory inhibitory pathway is involved in cell replication, and the endogenous neuropeptide OGF targets cyclin-dependent kinase inhibitors, p16 and/or p21. Blockade of OGF-OGFr interfacing by systemic or topical administration of opioid antagonists such as naltrexone (NTX) results in accelerated DNA synthesis, cell replication, and tissue repair. Molecular manipulation of OGFr using sense constructs delayed corneal re-epithelialization, whereas antisense constructs accelerated repair of the corneal surface. Corneal keratopathy, a significant complication of diabetes mellitus, is manifested by delays in corneal re-epithelialization following surgery, injury, or disease. Tissue culture studies have shown that addition of NTX stimulates DNA synthesis and explant outgrowth of rabbit corneal epithelium, whereas OGF depresses DNA synthesis and explant outgrowth in a receptor-mediated manner. NTX accelerated corneal re-epithelialization in organ cultures of human and rabbit cornea. Systemic application of NTX to the abraded corneas of rats, and topical administration of NTX to the injured rabbit ocular surface, increased re-epithelialization. Systemic injections or topical administration of NTX facilitates re-epithelialization of the cornea in diabetic rats. Given the vital role of the corneal epithelium in maintaining vision, the frequency of corneal complications related to diabetes (diabetic keratopathy), and the problems occurring in diabetic individuals postoperatively (e.g., vitrectomy), and that conventional therapies such as artificial tears and bandage contact lenses often fail, topical application of NTX merits clinical consideration.

Aldose reductase inhibitor counteracts the attenuated adhesion of human corneal epithelial cells induced by high glucose through modulation of MMP-10 expression

AIMS

We investigated the preventive effect of aldose reductase inhibitor (ARI) on the adhesion of SV40-transformed human corneal epithelial cells (HCECs) exposed to high glucose, and the underlying mechanism focusing on the role of matrix metalloproteinase (MMP)-10.

METHODS

HCECs were cultured in medium containing a normal (5.5 mM) or high (31.2 mM) concentration of D-glucose in the presence or absence of ARI, fidarestat. Cell attachment ability was evaluated by short-term adhesion assay. The levels of intracellular polyol were measured by liquid-gas chromatography. Real-time reverse transcriptase-polymerase chain reaction (RT-PCR), and Western blotting were used to determine the expression levels.

RESULTS

Decreased attachment activity and increased accumulation of polyol induced by exposure to high glucose were abrogated by ARI. Supply of recombinant MMP-10 decreased integrin alpha3beta1-expression and cell adhesion. The expression level of MMP-10 was enhanced at both protein and mRNA levels by exposure to high glucose, while that of integrin alpha3beta1 was decreased at the protein level, but remained unchanged at the mRNA level. These alterations in the expression levels of MMP-10 and integrin alpha3beta1 were normalized by ARI.

CONCLUSIONS

ARI counteracts the decreased adhesion of HCECs induced by high glucose exposure, through the modulation of the expression of MMP-10.

Étude des atteintes de la surface oculaire chez les patients diabétiques

INTRODUCTION

Diabetes mellitus leads to microvascular complications and altered basement membranes, which are partly responsible for ocular complications. Corneal nerve impairment is involved in ocular surface disease as well. We examined the possible relation between ocular surface signs and retinal or neuronal degenerative complications due to diabetes.

PATIENTS AND METHODS

Diabetics and control subjects were compared for corneal sensitivity and tear function parameters such as the Schirmer test, tear film break-up time (BUT), and fluorescein and lissamine green stainings. The relation of the duration of the disease, the stage of retinopathy, metabolic control (HbA1c), and diabetic peripheral neuropathy with ocular surface disorders were noted.

RESULTS

Twelve healthy patients were compared to 48 diabetics. The Schirmer test value, BUT, and fluorescein and lissamine green impregnations were significantly modified in diabetics compared to controls (p<0.0001), with no relation to the duration of the disease or metabolic control. The mean corneal sensitivity was significantly lower in diabetic patients (p<0.01), diabetics with peripheral neuropathy (p=0.00008), and diabetics with preproliferative retinopathy (p=0.0003). Tear function parameters were more frequently altered in patients presenting preproliferative retinopathy and peripheral neuropathy (p<0.001).

CONCLUSIONS

Diabetes can lead to ocular surface impairments with qualitative and quantitative tear disorders, all of which seem to evolve in close relation with retinopathy and peripheral neuropathy. These lacrymal and corneoconjunctival abnormalities, even if not currently mentioned by diabetic patients, can result in severe neurotrophic complications.

A randomised, placebo controlled clinical trial of the aldose reductase inhibitor CT-112 as management of corneal epithelial disorders in diabetic patients

AIM

To evaluate the efficacy of topical aldose reductase inhibitor CT-112 (5-[3-ethoxy-4-pentyloxyphenyl]-2,4-thiazolidinedione) on corneal epithelial barrier function in diabetic patients.

METHODS

This was a prospective, randomised, double masked placebo controlled study. 34 eyes of 34 diabetic patients were randomly assigned treatment with 0.25% eye drops of CT-112 (n = 22) or a placebo (n = 12) four times a day for 8 weeks. Corneal fluorescein staining and corneal sensation were examined before treatment as well as 4 and 8 weeks after administration. Corneal epithelial permeability to fluorescence was measured with an anterior fluorophotometer.

RESULTS

Average scores of superficial punctate keratopathy and corneal sensitivity did not differ significantly between the two groups at any time. Whereas average fluorescein concentrations did not differ significantly for the CT-112 and placebo groups before treatment, they did differ significantly 4 and 8 weeks after treatment (4 weeks, p = 0.0327; 8 weeks, p = 0.0143).

CONCLUSION

The topical aldose reductase inhibitor, CT-112 improves the corneal epithelial barrier function in diabetic patients.

Changes of tear film and ocular surface in diabetes mellitus

This study was performed to investigate the changes of tear film and ocular surface in diabetic patients, as well as the ocular and systemic factors related to these changes. We assessed the scoring of keratoepitheliopathy, corneal sensitivity test, tear film break-up time (BUT), Schirmer test, and conjunctival impression cytology in 94 eyes of 47 patients with noninsulin-dependent diabetes mellitus and in 60 eyes of 30 normal subjects. The degree of keratoepitheliopathy was severe, and the corneal sensitivity, BUT, and tear secretion were significantly reduced in the diabetic patients. Conjunctival impression cytology showed a higher grade of conjunctival squamous metaplasia and lower goblet cell density in the diabetic patients. All parameters were related to the status of metabolic control, diabetic neuropathy, and stage of diabetic retinopathy. We think that diabetic patients with poor metabolic control, neuropathy, and advanced stage of retinopathy should be examined for tear film and ocular surface changes.

Corneal epithelial barrier function in diabetic patients

PURPOSE

To evaluate the corneal epithelial barrier function in diabetic patients.

METHODS

In 29 eyes of 29 diabetic patients and 55 eyes of 55 nondiabetic controls, corneal epithelial permeability to fluorescein was measured using an anterior fluorophotometer. The average fluorescein concentration in the central cornea was compared between diabetic patients and controls. Multiple regression analysis was used to assess the factors that affect corneal epithelial barrier function in diabetic patients.

RESULTS

The average fluorescein concentrations in diabetic patients and nondiabetic controls were 44.1 +/- 25.3 ng/mL and 29.9 +/- 19.8 ng/mL (mean +/- SD), respectively (P = 0.0057, unpaired t test). An explanatory variable relevant to the impaired corneal epithelial barrier function was the serum hemoglobin A1c (HbA1c) concentration (standardized partial regression coefficient = 0.466, P = 0.0163).

CONCLUSIONS

The corneal epithelial barrier function is impaired in diabetic patients. Diabetic patients with higher serum HbA1c levels are more predisposed to impaired barrier function in the corneal epithelium.

Prolonged exposure to high glucose impaired cellular behavior of normal human corneal epithelial cells

PURPOSE

To determine the effect of prolonged exposure to high glucose on cellular behavior of normal human corneal epithelial cells (HCEC).

METHODS

HCEC were cultured in medium under normal or high glucose conditions for 14 days. Proliferation was evaluated by direct cell counting and [(3)H]thymidine incorporation. Cell cycle analysis was performed using flow cytometry. The ability of HCEC to attach to type I collagen was evaluated using a short-term colorimetric adhesion assay. The effect of high glucose on the expression of integrin alpha(3)beta(1) was also evaluated using flow cytometry.

RESULTS

Cell number and [(3)H]thymidine incorporation under high glucose conditions decreased compared with those under normal glucose conditions. The cells exposed to high glucose were G(0)/G(1) than untreated cells. The adhesion ability of HCEC under high glucose conditions decreased compared to normal glucose conditions. Expression of integrin alpha( 3)beta(1) was down-regulated under high glucose conditions.

CONCLUSIONS

High glucose had deleterious effects on cellular behavior of HCEC, which might cause delayed corneal epithelial wound healing in diabetic keratopathy.

Reduced need for corneal epithelial debridement during vitreo-retinal surgery using two different viscous surface lubricants

PURPOSE

Corneal clarity is frequently reduced during vitrectomy and scleral buckling surgery secondary to epithelial edema, requiring epithelial debridement to improve visibility. The presence of toxic preservatives in the corneal lubricant solutions is hypothesized to be a contributing factor to epithelial edema during vitreo-retinal surgery.

DESIGN

Interventional study.

METHODS

We compared prospectively the corneal clarity and epithelial debridement frequency in 71 patients within a single institution in whom either Goniosol (2.5% methylcellulose, boric acid, edetate disodium, sodium borate, potassium chloride, water, and 0.01% benzalkonium chloride) or GenTeal gel (0.3% hydoxypropyl-methylcellulose, carbopol 980, phosphonic acid, sorbitol, water, and 0.028% sodium perborate) was used as a corneal lubricant during the course of vitrectomy surgery using sutured contact lenses. Corneal clarity was subjectively graded in a scale of I to IV during surgery. Statistical analysis was made between these two groups for parametric and categorical data.

RESULTS

All eyes started with a corneal clarity grade of I (best possible). Corneal clarity decreased significantly faster in eyes where Goniosol was used to a median grade of III at 1 hour of surgical time. In eyes where GenTeal gel was used, corneal clarity decreased much slower, to a median grade of I at 1 hour of surgical time. The difference in frequency of epithelial debridement was also statistically significant: 54% and 14% for Goniosol and GenTeal eyes, respectively. Other factors that may cause corneal epithelial edema and affect corneal clarity were not statistically different between the Goniosol and the GenTeal groups, including median operative time, estimated intraocular pressure, pre- and intraoperative topical solutions and medications, and number of prior ocular procedures.

CONCLUSIONS

The use of GenTeal gel as a corneal lubricant maintains corneal clarity longer than Goniosol during the course of vitrectomy surgery using a contact lens viewing system, limiting the need for epithelial debridement.

Assessment of induced corneal hypoxia in diabetic patients

PURPOSE

To assess the control of corneal hydration in patients with diabetes during a contact lens-induced hypoxia.

METHODS

Corneal stress was induced in 15 patients with diabetes and 23 healthy patients by having them wear contact lenses for 2 hours. Pachymetries were measured and corneal parameters (percentage recovery per hour [PRPH], time for deswelling [T99%] and induced swelling [IS]) were calculated. In the mean time, tears were collected to assess the activity of lactate dehydrogenase (LDH), and a specular microscopy (SM) was performed.

RESULTS

In patients with diabetes, PRPH, T99%, and LDH activity were statistically significantly modified (p < 0.05), whereas IS and SM were not.

CONCLUSION

This decreased ability to recover the initial corneal thickness after a transient edema caused by hypoxia confirms the enzymatic dysfunction of the endothelial pumps that are partly caused by a shift toward anaerobic metabolism.

Ocular and systemic factors relevant to diabetic keratoepitheliopathy

PURPOSE

This study examines the contribution of ocular and systemic factors to diabetic keratoepitheliopathy.

METHODS

The presence and severity of keratoepitheliopathy was investigated in 114 eyes of patients with diabetes and 59 eyes of patients without diabetes. The ocular factors examined were the status of the lipid layer of the tear fluid assessed with the specular reflection video-recording system, corneal sensitivity using the Cochet-Bonnet method, tear volume by the cotton thread test, tear film stability by tear breakup time, and grade of diabetic retinopathy. The systemic factors examined included patient age, hemoglobin A1c value, and duration of diabetes mellitus. Multivariate regression analysis was performed to assess the factors related to keratoepitheliopathy.

RESULTS

The incidence of keratoepitheliopathy was 22.8% and 8.5% in patients with and without diabetes, respectively. Ocular measures, such as nonuniformity of tear lipid layer, corneal sensitivity, and tear breakup time, were significantly worse in patients with diabetes than in patients without diabetes ( p < 0.05). Multivariate regression analysis showed that the status of the tear lipid layer was significantly relevant to diabetic keratoepitheliopathy ( p < 0.05).

CONCLUSION

Qualitative abnormalities in tear secretion seem relevant to the development of diabetic keratoepitheliopathy. The tear lipid layer interference pattern may yield useful information for the elucidation of the mechanism and treatment of diabetic keratoepitheliopathy.