Effect of obstructive sleep apnea syndrome on corneal thickness

The Impact of Donor History of Sleep Apnea on Corneal Tissue Evaluation Parameters

PURPOSE

The goal of this study was to explore whether the donor history of sleep apnea affects corneal tissue evaluation parameters.

METHODS

This was a retrospective study assessing the impact of donor history of sleep apnea in a dataset obtained from the Eversight Eye Bank. Comparative analysis and multivariate regression were used to assess differences in key parameters including endothelial cell density (ECD) and central corneal thickness.

RESULTS

Data analyzed consisted of 50,170 tissues from 25,399 donors with no history of sleep apnea and 5473 tissues from 2774 donors with a history of sleep apnea. Tissue from donors with a history of sleep apnea showed lower ECD than those from donors with no history of sleep apnea (-51 cells/mm2, P < 0.001). Multivariate linear regression demonstrated that history of sleep apnea was a predictor of lower ECD by 13.72 cells/mm2 (P = 0.0264). Secondary analysis demonstrated that underweight and obese body mass indexes were significant predictors of increased ECD in donors with no history of sleep apnea (P < 0.0001, P = 0.025, respectively). Body mass index category was not a significant predictor of ECD in donors with a history of sleep apnea. In a smaller subset of 10,756 tissues, sleep apnea was not a significant predictor of central corneal thickness.

CONCLUSIONS

This is the first study to demonstrate that a donor's history of sleep apnea is associated with a lower ECD in a large eye bank dataset. Future studies are needed to investigate whether history of sleep apnea affects posttransplantation outcomes.

Aqueous Humor Circulation in the Era of Minimally Invasive Surgery for Glaucoma

Glaucoma surgery with implantation of aqueous humor draining microstents may compromise long-term corneal health by disrupting aqueous humor circulation. The effect of stent numbers on this circulation was interrogated to determine the number of stents associated with minimal circulation disruption. An in vitro anterior eye model perfusion system was constructed with multiple exit ports. A 3-D model of the anterior eye was imported into ABAQUS CFD, analyzes were carried out for unsteady laminar flow and solved using Navier-Stokes equations. DT Vision Foundry was used to analyze velocity contour plot images. The field variable results output for the CFD model were fluid wall shear, fluid pressure and fluid velocity. In vitro, "aqueous" fluid flow is high through a single stent and "aqueous" stagnation is greatest in the quadrants 180° away. Increasing stent port numbers, results in an exponential decrease in the stagnant flow locations. High wall shear stress was seen in the single stent model and is markedly reduced after a second and subsequent stents are introduced. We identify two factors potentially contributing to corneal compromise post glaucoma drainage surgery: aqueous humor stagnation, remote to the stent site and higher exit flows imparting increased stent exit shear stress (particularly with a single stent). With 4 stents, there is minimal disruption of anterior chamber circulation (mimicking physiological conditions). Furthermore we propose that aqueous humor circulation disruption via the usual single-exit port approach disrupts aqueous humor circulation with long-term consequences for corneal health.

Analysis of corneal topographic and endothelial cell properties in newly diagnosed obstructive sleep apnea patients: A case-control study

PURPOSE

To investigate the topographic features and endothelial cell changes in the corneas of patients with newly diagnosed obstructive sleep apnea (OSA).

BACKGROUND

This cross-sectional case-control study included 98 patients with OSA and 90 healthy controls. OSA was diagnosed on the basis of a polysomnographic sleep examination. Patients with OSA were grouped according to their apnea-hypopnea index (AHI) scores. Corneal topographic measurements were obtained using the Scheimpflug-Placido disk topographer, and keratometry values, anterior chamber parameters, thinnest corneal thickness, symmetry index (SI), keratoconus vertex (KV), and the Baiocchi-Calossi-Versaci index, including keratoconus (KC) screening indexes, were recorded. The corneal endothelium was visualizedby specular microscopy, and the endothelial cell density, coefficient of variability (CV), and percentage of hexagonal cells (HEX) were recorded.

RESULTS

In this study, 32 patients had mild, 34 patients had moderate, and 32 patients had severe OSA. The mean back KV (KVb) and back SI values were significantly higher in the OSA group than in the control group (P <0.001, P = 0.035, respectively). As body mass index (BMI) increased, KVb also increased significantly (r = 0.281; P = 0.009). The mean CV and HEX values differed significantly between the OSA and control groups (P = 0.012 and P = 0.002, respectively). In addition, a significant correlation was found between AHI and KVb and CV values (r = 0.315; P <0.001 and r = 0.231; P = 0.011, respectively).

CONCLUSIONS

This study revealed abnormal changes in the corneal endothelial morphology and topographic KC screening indexes in relation to OSA severity in patients and controls. Further research is required to determine the effect of BMI on corneal topographic findings in patients with OSA.

Ocular manifestations of common pulmonary diseases: a narrative review

Several pulmonary disorders can cause ocular involvement. Understanding these manifestations is critical for early diagnosis and treatment. Hence, we set out to examine the most common ocular manifestations of asthma, chronic obstructive pulmonary disease (COPD), sarcoidosis, obstructive sleep apnea (OSA), and lung cancer. Allergic keratoconjunctivitis and dry eye are two ocular manifestations of bronchial asthma. The inhaled corticosteroids used to treat asthma can cause cataract formation. COPD is associated with ocular microvascular changes as a result of chronic hypoxia and systemic inflammation spillover into the eyes. Its clinical significance, however, is unknown. Ocular involvement is common in sarcoidosis, occurring in 20% of cases of pulmonary sarcoidosis. It can affect nearly any anatomical structure of the eye. Obstructive sleep apnea has been linked to floppy eye syndrome, glaucoma, non-arteritic anterior ischemic optic neuropathy, keratoconus, retinal vein occlusion, and central serous retinopathy, according to research. However, while an association has been established, causality has yet to be established. The effect of positive airway pressure (PAP) therapy used to treat OSA on the aforementioned ocular conditions is unknown. PAP therapy can cause eye irritation and dryness. Lung cancer can affect the eyes through direct nerve invasion, ocular metastasis, or as part of a paraneoplastic syndrome. The goal of this narrative review is to raise awareness about the link between ocular and pulmonary disorders in order to aid in the early detection and treatment of these conditions.

Obsructive sleep apnea syndrome: is it a risk factor for ocular surface disease and ocular comorbidities?

PURPOSE

To investigate the accompanying ocular findings in patients with obstructive sleep apnea syndrome (OSAS) and evaluate the susceptibility to ophthalmological diseases.

MATERIALS AND METHODS

In this cross-sectional study, qualifying study subjects were patients who had been diagnosed with severe OSAS (apnea/hypopnea index (AHI > 30/h), n = 31), and control subjects (n = 30) who had an AHI index of < 5 (as normal). General ophthalmological examination, eyelid laxity measurements, corneal topography, visual field, retinal nerve fiber layer parameters, dry eye tests were performed on the patients.

RESULTS

It was observed that the two groups had similar characteristics in terms of gender, age, presence of hypertension, diabetes, and body mass index. According to eyelid laxity measurements, the incidence of loose eyelids was higher in the OSAS patient group. Choroidal thickness was thinner in the study group than in the control group. Schirmer test and tear break-up time were significantly lower in the study group than in the control group. The percentage of meibomian gland loss in meibography and the ocular surface disease index score for symptoms was significantly higher in the study group than in the control group.

CONCLUSION

In this study, we found significant changes in ocular surface parameters, eyelid laxity, choroidal thickness, and visual field indices in OSAS patients. Dry eye syndrome might be related eyelid laxity and inflammation in OSAS patients. Early diagnosis and follow-up of ocular diseases in OSAS, which affect the quality of life and visual prognosis in advanced ages, are important.

Comparison of obstructive sleep apnea syndrome and keratoconus patients on elevation maps

PURPOSE

This study aimed to compare the tomographic features of the cornea on elevation maps between obstructive sleep apnea syndrome (OSAS) and keratoconus (KC) patients and to investigate the presence of susceptibility to ectatic corneal diseases in OSAS patients.

DESIGN

This is a comparative cross-sectional case-control study.

METHODS

This study included 84 eyes of 42 patients diagnosed with severe OSAS using polysomnography (apnea/hypopnea index > 30), 84 eyes of 56 patients diagnosed with keratoconus, and 84 eyes of 42 healthy subjects as control group and evaluated in three groups. Elevation maps of all the groups were performed using Pentacam, and topometric, pachymetric, and deviation indices were recorded.

RESULTS

The study included 252 eyes of 130 participants divided in three groups. Comparing all the tomographic keratometric values, a significant difference was found among the three groups. All keratometric values were found to be higher in the OSAS patients group compared to those in the control group. Also topometric indices and Belin-Ambrosio enhanced ectasia display (BAD) were observed to be higher as in subclinical keratoconus and statistically significant when compared to those in the control group.

CONCLUSION

The study reveals the tomographic corneal characteristics and topometric and pachymetric indices of patients with severe OSAS at the time of diagnosis; these findings statistically significantly differ from the control group. In addition to the known association of floppy eyelid in OSAS patients, the suspicion of keratoconus should be kept in mind.

Corneal Endothelial Morphology and Thickness Alterations in Patients With Severe Obstructive Sleep Apnea-Hypopnea Syndrome

PURPOSE

To investigate central endothelial cell density (ECD), morphology, and central corneal thickness (CCT) in patients newly diagnosed with severe obstructive sleep apnea-hypopnea syndrome (OSAHS) and to determine the correlation between these parameters and OSAHS severity.

METHODS

This prospective, comparative case series was conducted in a university ophthalmology clinic. In total, 51 patients recently diagnosed with severe OSAHS (apnea-hypopnea index above 30) and a paired, age and sex-matched control group of 44 healthy individuals were enrolled. After detailed ophthalmologic examination, specular microscopy measurement was performed for all participants. Central ECD, average cell area, coefficient of variation (CV) of cell area, hexagonal cell appearance ratio (% Hex), and CCT were compared between the groups. The Pearson correlation test was also used to assess the influence of the polysomnographic findings, that is, the proportion of each stage of sleep, apnea-hypopnea index, SpO2, mean and maximum duration of apneas, oxygen desaturation index, and arousal index on corneal endothelial morphometric parameters and CCT.

RESULTS

A total of 190 eyes were examined: 102 eyes of patients with severe OSAHS and 88 eyes of the control group. The mean ECD, CV, % Hex, and CCT values in the OSAHS group were 2439.25 ± 344.36 cells/mm, 41.41 ± 11.62, 45.22 ± 7.06%, and 533.88 ± 40.53 μm, respectively. ECD and CCT did not significantly differ between the groups (P = 0.46, P = 0.55, respectively). CV value was significantly higher (P = 0.009), whereas the %Hex was significantly lower (P = 0.01) in the OSAHS group. We observed a significant negative correlation between CCT and REM sleep percentage (P = 0.005).

CONCLUSIONS

Greater pleomorphism and polymegathism of corneal endothelium was found in patients with severe OSAHS when compared with healthy subjects. Low percentage of REM sleep, usually found in patients with OSAHS, may cause an increase in corneal thickness.

The Associations of Obstructive Sleep Apnea and Eye Disorders: Potential Insights into Pathogenesis and Treatment

Purpose of Review

Obstructive sleep apnea (OSA) patients are at significantly increased risks for cardiovascular and cerebrovascular morbidities. Recently, there has been heightened interest in the association of OSA with numerous ocular diseases and possible improvement of these conditions with the initiation of OSA treatment. We reviewed the current evidence with an emphasis on the overlapping pathogeneses of both diseases.

Recent Findings

Currently available literature points to a substantial association of OSA with ocular diseases, ranging from those involving the eyelid to optic neuropathies and retinal vascular diseases. Since the retina is one of the highest oxygen-consuming tissues in the body, the intermittent hypoxia and hypercapnia ensuing in OSA can have deleterious effects on ocular function and health. Tissue hypoxia, autonomic dysfunction, microvascular dysfunction, and inflammation all play important roles in the pathogenesis of both OSA and ocular diseases. Whether OSA treatment is capable of reversing the course of associated ocular diseases remains to be determined. It is anticipated that future therapeutic approaches will target the common underlying pathophysiologic mechanisms and promote favorable effects on the treatment of known associated ocular diseases.

Summary

Emerging evidence supports the association of ocular diseases with untreated OSA. Future studies focusing on whether therapeutic approaches targeting the common pathophysiologic mechanisms will be beneficial for the course of both diseases are warranted.

Thinning of the inner and outer retinal layers, including the ganglion cell layer and photoreceptor layers, in obstructive sleep apnea and hypopnea syndrome unrelated to the disease severity

PURPOSE

The aim of this study was to analyze the segmented layers of the macula in patients with obstructive sleep apnea and hypopnea syndrome (OSAS) using spectral domain optical coherence tomography (SD-OCT).

MATERIAL AND METHODS

This single-center, cross-sectional study included 31 OSAS patients and 31 age- and gender-matched control subjects. SD-OCT and overnight polysomnography were performed on all participants. The OSAS patients were categorized according to disease severity (mild, moderate, severe). The groups were compared in respect of each segmented macular layer through the use of segmentation software on SD-OCT. Total retinal thickness (RT), peripapillary retina nerve fiber layer (pRNFL) thickness, central corneal thickness (CCT) and intraocular pressure (IOP) values were also compared between the groups.

RESULTS

Mean CCT (p:0.015) and nasal pRNFL values (p:0.042) were lower and mean IOP was higher (p:0.018) in OSAS patients than in the control group. The statistical analysis revealed significantly thinner total RT, inner retinal layers (IRL), outer retinal layers (ORL), photoreceptor layers (PRL) and ganglion cell layer (GCL) thicknesses in the OSAS groups compared to healthy subjects. No significant differences were found between the three OSAS subgroups in all segmented macular layers and pRNFL measurements.

CONCLUSION

The results of this study showed relatively thinner nasal pRNFL, total RT, IRL, ORL, PRL and GCL layers in OSAS patients compared to healthy subjects. Moreover, this thinning of the segmented layers was unrelated to disease severity.

Evaluation of corneal endothelium using specular microscopy in patients with obstructive sleep apnea syndrome

PURPOSE

In the present study we evaluate the corneal endothelium using specular microscopy in patients with obstructive sleep apnea syndrome (OSAS).

METHODS

The study included a total of 100 patients including 35 patients with mild OSAS, 34 patients with moderate OSAS and 31 patients with severe OSAS, and the right eyes of 30 patients as a control group. Patients were examined to exclude the possibility of ocular diseases. Cellular density in the cornea epithelium (cell/mm²), corneal thickness (µ), percentage of hexagonal cells (%) and the coefficient of variation were evaluated using a specular microscope.

RESULTS

Corneal thickness was significantly decreased in all OSAS groups when compared to the control group (p = 0.002), while no significant difference was identified among the OSAS groups. The corneal endothelial cell density, percentage of hexagonal cells and coefficient of variation were significantly different between the OSAS groups and the control group (p < 0.001).

CONCLUSION

More significant impairments were noted in the corneal endothelium of the patients in the OSAS group than in the control group, and specular microscopy is in valuable in the follow-up and treatment of such patients.

Effects of Continuous Positive Airway Pressure Treatment for Obstructive Sleep Apnea-Hypopnea Syndrome on Corneal Morphological Characteristics

PURPOSE

To evaluate the effects of continuous positive airway pressure (CPAP) therapy on corneal endothelial morphometry and pachymetry in patients with obstructive sleep apnea-hypopnea syndrome (OSAHS).

METHODS

This prospective, observational study included patients with OSAHS who were evaluated right before and after the commencement of CPAP treatment. Each patient underwent a detailed ophthalmologic examination and assessment of their corneal endothelium with a noncontact specular microscope (Tomey EM-3000; Tomey Corp). Endothelial cell density, coefficient of variation of cell area (CV), hexagonal cell appearance ratio (%Hex), and central corneal thickness were measured. The post-CPAP results were compared with the results of a control group. The differences in the corneal parameters between pre- and post-CPAP therapy of the OSAHS group were correlated with the pretreatment polysomnography results.

RESULTS

Twenty-seven distinct eyes of 27 patients recently diagnosed with OSAHS and 30 eyes of 30 healthy individuals were used for the statistical analysis. The mean age of patients with OSAHS was 54.2 ± 11.8 years, and after 9.6 months (range 3-18 mo) of good adherence to CPAP treatment, their CV values, indicating polymegathism, decreased from 41.7 ± 8.7 to 38.3 ± 5.8 (P = 0.04), whereas %Hex, indicating pleomorphism, increased from 45.8% ± 8.2% to 48.4% ± 6.6% (P = 0.008). Their post-CPAP corneal parameters did not differ significantly from those of the control group (P > 0.05). A significant positive correlation was observed between the decrease in CV and the duration of the treatment (Rs = 0.566, P = 0.002), as well as the pre-CPAP nonrapid eye movement (NREM) sleep percentage (Rs = 0.459, P = 0.02). A negative correlation was noted between the decrease in CV and the percentage of rapid eye movement (REM) sleep (Rs = -0.459, P = 0.02).

CONCLUSIONS

Better oxygenation during sleep, resulting from increased CPAP adherence, had a significant influence on corneal endothelium, providing an improvement in corneal polymegathism and pleomorphism, with a potential return of CV and %Hex to their normal values. Greater improvement in polymegathism was observed in patients with greater proportion of NREM sleep.

Corneal Topographic, Anatomic, and Biomechanical Properties in Severe Obstructive Sleep Apnea-Hypopnea Syndrome

PURPOSE

To determine corneal topographic, anatomic, and biomechanical properties in patients newly diagnosed with severe obstructive sleep apnea-hypopnea syndrome (OSAHS).

METHODS

This is a cross-sectional study including 25 patients recently diagnosed with severe OSAHS (apnea-hypopnea index above 30) and a paired control group of 25 healthy subjects. All patients underwent a complete eye examination with an elevation topography Pentacam Scheimpflug study and a study with Reichert Ocular Response Analyzer, collecting several topographic, anatomic, and biomechanical variables.

RESULTS

Fifty eyes of 25 patients (23 of them were men) diagnosed with OSAHS by somnography and the same number of healthy subjects (23 of them were men) were included, with an average age of 64 ± 11 years (range 45-78 years) for cases and an average age of 64 ± 11 years (range 45-81 years) for the controls. No differences were found in keratometry, cylinder, refractive indexes, Bad-D, or pachymetry. The mean corneal volume for cases was 58.64 ± 3.05 mm and for the controls 60.48 ± 3.33 mm (P = 0.005). The mean minimum radius for cases was 7.49 ± 0.31 and for the controls 7.36 ± 0.30 (P = 0.035). The mean elevation in apex for cases was 8.46 ± 5.18 and for the controls 2.38 ± 2.36 (P ≤ 0.001). Two eyes with a topographic diagnosis of keratoconus (KC) and another 6 with subclinical KC were detected using the Pentacam in the OSAHS group.

CONCLUSIONS

Many of the corneal topographic and biomechanical variables in patients with severe OSAHS present different values from the general population with a trend toward KC values, such as keratoconus index or paired keratoconus index. Compared with the control group, significant differences were found in corneal volume, corneal elevation, and minimum radius.

Effect of Obstructive Sleep Apnea on Corneal Morphological Characteristics

PURPOSE

To determine central corneal thickness (CCT) and the corneal parameters in patients with obstructive sleep apnea (OSA), evaluate the relationship between the severity of OSA, minimum peripheral capillary oxygen saturation (min. SpO2), and corneal morphological characteristics.

METHODS

Patients with OSA diagnosed by full-night polysomnography before treatment were included. Patients with OSA were divided into 3 groups according to the Apnea-Hypopnea Index (AHI). The control group (CG) was examined to exclude the possibility of OSA and ocular diseases. The following data were recorded: age, sex, body mass index, ophthalmologic evaluation, and the results of polysomnography.

RESULTS

A total of 114 eyes were studied: 74 eyes of patients with OSA and 40 eyes of the CG. The mean age was 57 ± 6 years. The mean values of CCT and endothelial cell density (ECD) varied significantly between the patients and the CG (P < 0.001). The mean values of CCT, ECD, cell variation coefficient (CV), and hexagonal cell percentage (HEX) in the group of patients with OSA were 535.28 ± 21.32 μm, 2632 ± 333, cells/mm. 31.8 ± 3.9, and 55.6 ± 6.9%, respectively. The mean CCT and ECD values for each group were lower than those for the CG. A significant negative correlation was found between CCT and ECD for AHI values (r = -0.390, P = 0.011 and r = -0.109, P = 0.040, respectively), and a weak positive correlation between CCT and ECD was found for min. SpO2 (r = 0.282, P = 0.020 and r = 0.332, P = 0.018, respectively). CV and HEX did not significantly differ between the groups and did not correlate with the results of polysomnography.

CONCLUSIONS

Hypoxia is associated with significant changes in CCT and ECD. In patients with OSA, these parameters varied significantly when compared with the subjects in the CG. The severity of hypoxemia and the increase in AHI values reduce CCT and ECD in patients.

Evaluation of Intraocular pressure, Corneal thickness, and Retinal nerve fiber layer thickness in patients with Obstructive Sleep Apnea Syndrome

Objective:

To evaluate the intraocular pressure (IOP), central corneal thickness (CCT), and peripapillary retinal nerve fiber layer (RNFL) thickness in Patients with Obstructive Sleep Apnea Syndrome.

Methods:

In this prospective study, 103 patients with OSAS (study group) and 37 healthy subjects were enrolled. All participants underwent comprehensive ophthalmic examinations. Mean outcome measures were intraocular pressure by Goldmann applanation tonometry, CCT measurement using ultrasound pachymeter and peripapillary RNFL thickness measured by spectral-domain optical coherence tomography.

Results:

The differences between the mean values of RNFL thickness in all quadrants were similar in both groups and were not statistically significant (p=0.274). The IOP and CCT measurement averages of all patients with OSAS were lower than the control group. However, this difference was not statistically significant. There was no correlation between the apnea-hypopnea index, lowest oxygen saturation (LAST) or Body Mass Index (BMI) and the peripapillary RNFL thickness, IOP or CCT when OSAS group was divided by severity.

Conclusions:

The study results suggest that peripapillary RNFL thickness, IOP or CCT did not differ significantly between OSAS and control groups. We also found no correlation between apnea severity (AHI), lowest oxygen saturation (LAST) and BMI and RNFL, CCT and IOP.