October 2017

NEWS & OPINION

Research highlight
Study links obstructive sleep apnea in type 2 diabetes patients to higher risk for sight-threatening condition


by Liz Hillman EyeWorld Staff Writer

Those with both diabetes and OSA were at greater risk of developing diabetic retinopathy within 4 years

New research is reminding ophthalmologists about the importance of considering the effect of a patient’s quality of sleep on ocular disease and probing deeper if patients report having symptoms that might be indicative of obstructive sleep apnea (OSA), especially if they’re diabetic.
Research published in the American Journal of Respiratory and Critical Care Medicine found that patients with type 2 diabetes and OSA had a greater risk of developing sight-threatening diabetic retinopathy (DR) in 4 years or less.1
“OSA and hyperglycemia have similar molecular consequences that can lead to the development of diabetes-related microvascular complications including DR,” said Abd Tahrani, MD, clinician scientist, National Institute for Health Research, University of Birmingham Institute of Metabolism and Systems Research, Birmingham, U.K. “Hypoxemia, oxidative stress, inflammation, endothelial dysfunction, and hypertension all play an important role in the pathogenesis of DR. OSA is associated with multiple DR risk factors, including intermittent oxygen desaturations, increased inflammation and oxidative stress, and endothelial dysfunction. Hence, we hypothesized that OSA was linked to DR.
“As tissue, hypoxia and vascular endothelial growth factor (VEGF) play important roles in the development of pre-proliferative and proliferative DR, we were expecting that OSA—with it associated hypoxemia—would result in the development of advanced DR,” Dr. Tahrani said.
The longitudinal study from two U.K.-based diabetes clinics involved 230 patients, 36.1% of whom had sight-threatening diabetic retinopathy and 63.9% had OSA. Sight-threatening diabetic retinopathy was more prevalent in patients with OSA (42.9%) compared to those without OSA (24.1%).
The median follow-up period was 42.0 months, and the researchers found that patients with OSA were more likely to develop pre-proliferative or proliferative DR compared to patients without OSA (18.4% compared to 6.1%). Patients who were treated with continuous positive away pressure were less likely to develop pre-proliferative or proliferative DR.
Dr. Tahrani noted that the patients included in the study were a higher risk population with multiple risk factors for diabetic retinopathy progression. “… it is worth noting that the vast majority of progression occurred in patients who had background retinopathy at baseline, who are typically at increased risk of progression compared to patients with no retinopathy,” Dr. Tahrani said, adding that it could be useful to repeat the study in a lower risk population and for a longer follow- up period.
Obstructive sleep apnea has been implicated as causing or contributing to other ophthalmic diseases or conditions as well, including floppy eyelid syndrome, papilledema, glaucoma, and nonarteritic anterior ischemic optic neuropathy.2–5
Nina Ni, MD, Eye Care Institute, Santa Rosa, California, said that while sleep apnea is not a condition asked about on her pre-appointment questionnaire—many patients, she noted, don’t even know they have it—as a cornea and external disease specialist, she gets a lot of referrals for lid issues.
“We know that OSA is associated with floppy eyelid syndrome. Sometimes when patients are sleeping, the eyelid may evert and can rub and often times they get an upper lid reaction when it’s so lax,” Dr. Ni said. “[Sleep apnea] is always on my radar for that reason, and I think that it’s also on the general ophthalmologist’s radar for that reason.”
Dr. Ni will counsel these patients to use lubrication at night—a thick ointment or gel artificial tears —and might even advise them to tape their lid shut. If this is too conservative of a treatment, she might refer them to an oculoplastic surgeon.
As for the sleep apnea, which can have other systemic effects, Dr. Ni said she will include that a sleep evaluation might be a worthwhile workup in her letter to the patient’s primary care physician.
“Individuals with OSA have a dramatically increased prevalence and severity of potentially sight-threatening, proliferative diabetic retinopathy and maculopathy due to a multifactorial combination of obesity, glucose intolerance, glucose resistance, metabolic disturbances, and systemic hypertension—all of which individually and more so in damaging combinations can precipitate diabetic retinopathy,” said Alan Mendelson, MD, Eye
Surgeons and Consultants, Hollywood, Florida. “Weight loss, enhanced diabetic control, improvement in the metabolic disturbances, and well-controlled blood pressure have all slowed or eliminated progression of retinopathy and simultaneously reduced the risk of other systemic microvascular complications of diabetes. In essence, all individuals with OSA should be monitored vigilantly by their pulmonologist, endocrinologist, cardiologist, and ophthalmologist.”
“It is also important to recognize that patients with DR are at increased risk of having OSA and that having OSA will increase the risk of progression to advanced DR,” Dr. Tahrani said. “Hence, it is important to have a low threshold for assessing the possibility of OSA in these patients. Performing sleep studies, via the appropriate specialists, would be ideal, but even simple questions related to OSA symptoms, such as snoring, witnessed apneas, and the presence of excessive daytime sleepiness, will aid ophthalmologists in making decisions regarding the need for further investigations for OSA. There are also several available validated questionnaires that can be used to assess the OSA risk in patients before doing sleep studies.
“Finally, while we still do not know for sure whether OSA treatment can reduce the risk of progression to advanced DR, it is important to recognize that OSA treatment will have an impact on other important aspects, including improvements in OSA-related symptoms, lowering the blood pressure, lowering the risk of road traffic accidents, and improving the patient’s quality of life.”

References

1. Altaf QA, et al. Obstructive sleep apnoea and retinopathy in patients with type 2 diabetes: A longitudinal study. Am J Respir Crit Care Med. 2017 June 8. Epub ahead of print.
2. McNab AA. Floppy eyelid syndrome and obstructive sleep apnea. Ophthal Plast Reconstr Surg. 1997;13:98–114.
3. Purvin VA, et al. Papilledema and obstructive sleep apnea syndrome. Arch Ophthalmol. 2000;118:1626–30.
4. Chaitanya A, et al. Glaucoma and its association with obstructive sleep apnea: A narrative review. Oman J Ophthalmol. 2016;9:125–34.
5. Archer EL, et al. Obstructive sleep apnea and nonarteritic anterior ischemic optic neuropathy: Evidence for an association. J Clin Sleep Med. 2013;9:613–18.

Editors’ note: Drs. Tahrani, Ni, and Mendelson have no financial interests related to their comments.

Contact information

Mendelson
: karensuedennis@gmail.com
Ni: ninani66@gmail.com
Tahrani: A.A.Tahrani@bham.ac.uk

Study links obstructive sleep apnea in type 2 diabetes patients to higher risk for sight-threatening condition Study links obstructive sleep apnea in type 2 diabetes patients to higher risk for sight-threatening condition
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