Impact of Diabetes on Visual Function in Veterans with Optic Disc Drusen: A Comparative Study

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doi:10.62055/30451521Fc

ABSTRACT

Optic disc drusen (ODD) are present in up to 2% of the general population. The presence of ODD can result in vision loss. This study investigated whether individuals with ODD and a diagnosis of diabetes had worse visual function compared with those who had ODD but did not have diabetes. A retrospective chart review was conducted on patients seen for eye care within Veterans Affairs Portland Health Care System. Data were gathered regarding visual acuity, visual field performance, and systemic health on 102 Veterans. Neither visual acuity nor visual field mean deviation was significantly worse in individuals with Diabetes Mellitus (DM) compared with those without DM. We concluded that DM patients with ODD may not require closer follow-up than non-diabetic patients with ODD.

INTRODUCTION

Optic disc drusen (ODD) are acellular calcific deposits that contain mucopolysaccharides, amino acids, deoxyribonucleic acid, ribonucleic acid, and iron.¹ Often these deposits are found anterior to the lamina cribrosa and behind Bruch’s membrane, though on rare occasion, they may be posterior to the lamina cribrosa or protruding into the vitreous.¹ The prevalence ranges from 0.34-2% in the general population and is seen bilaterally in 65-90% of cases.¹ ODD are found more often in females, Caucasians, and patients with small, crowded optic discs with abnormal vasculature.² Ocular complications of optic disc drusen include disc hemorrhage, non-arteritic ischemic optic neuropathy, vascular occlusions, peripapillary choroidal neovascular membrane, and visual field loss that can lead to legal blindness. However, no studies to date have identified an association between common systemic conditions and vision loss in patients with ODD despite a known association between diabetes and worsening visual field in other optic nerve head conditions such as glaucoma.³ This retrospective study reviewed the visual impact of ODD in an adult population over a 7-year period in the Veterans Affairs Portland Health Care System and compared visual function of patients with and without diabetes mellitus. We investigated whether diabetes is associated with worse visual function among individuals who have ODD compared with those who had ODD but did not have diabetes.

METHODS

This study was reviewed and approved by the VA Portland Health Care System Institutional Review Board and conforms with the principles and applicable guidelines for the protection of human subjects in biomedical research. A cross-sectional analysis was conducted from data collected by a chart review of individuals who received care at Veterans Affairs Portland Health Care Systems (VAPORHCS) between January 1, 2010 and December 31, 2017.

Primary care examination notes were reviewed to determine whether the individual had a diagnosis of diabetes, the primary independent variable. The outcome of interest was visual field mean deviation of the better eye as measured on Humphrey Visual Field Analyzer II, 24-2 Swedish Interactive threshold algorithm standard program, white on white, static perimetry (Carl Zeiss Meditec, in Dublin, CA, USA.) Data were collected on age, race, gender, diagnosis of hypertension, high cholesterol, obstructive sleep apnea, migraine, and ocular hypertension.

Analytic Sample

Individuals included in this study were those who had ICD-9 or ICD-10 codes for optic disc drusen and had an established primary care provider with at least one visit during that time frame at VAPORHCS and at least two Humphrey Visual Field 24-2 performed, one of which had to be deemed reliable using criteria outlined in the Ocular Hypertension Treatment Trial which were less than 33% false positives, false negatives and fixation losses.⁴ Individuals were excluded from analysis if they had concurrent optic nerve or retinal disease, significant media opacity, or a neurological visual field defect.

During the chart review process, the primary care examination record closest to the date of the most recent eye examination in which ODD was listed as a diagnosis was reviewed to obtain data regarding whether the patient had diabetes, hypertension, high cholesterol, obstructive sleep apnea, or migraine.^5–8 The eye examination record was reviewed to obtain data on visual acuity. The most recent visual field was reviewed with data collected on mean deviation, pattern standard deviation, and type of visual field defect. The type of defect was classified according to the criteria used in the Ocular Hypertension Treatment Trial .⁴

If there was uncertainty regarding the diagnosis of ODD, the researcher would review available records and special testing to make a final determination on the presence of optic disc drusen in the patient. Any diagnoses that were still in question were reviewed by a second researcher. If it was still not possible to determine the presence of ODD, the individual was excluded.

Statistical Methods

The statistical method counts and percentages was used to examine the distribution of each categorical variable. For continuous variables, the distribution was examined and the mean and standard deviation reported. To determine statistically significant differences between those with DM and those without, a chi-squared test was used for categorical variables and t-test was used for continuous variables. All values for visual acuity and visual field mean deviation are reported for the better seeing eye in each subject.

Since the purpose of this investigation was to compare visual function between two groups, a t-test was used to compare the mean values of visual field mean deviation between the two groups. Chi-squared analysis was used to examine differences in the types of visual field defects and categories of visual acuity between the two groups. Analysis was conducted using STATA 17.0 statistical software.

RESULTS

Of the 485 records reviewed, 104 were determined to have been coded incorrectly and were excluded. Two or more visual fields with reliability indices of less than 33% false positives, false negatives and fixation losses were necessary for inclusion in our field analyses. Of the remaining 381 individuals, only 129 had at least 2 Humphrey Visual Field 24-2 test results available for analysis. Upon further chart review, 27 of the remaining individuals had an identifiable cause of visual field defect other than optic disc drusen, leaving the final analytic sample of 102 individuals (Figure 1).

Figure 1. Derivation of the analytic sample.

A total of 39 (38.2%) individuals in the final sample had a diagnosis of diabetes and 63 (61.8%) did not have diabetes. The mean age was 64.8 years (SD 12.6), the demographic distribution was predominantly male (n=89, 87.3%), white (n=87, 85.3%), and had a diagnosis of hypertension (n=67, 65.7%). Individuals with DM more frequently also had hypertension (p<0.001), high cholesterol (p=0.02), and were older (p<0.01) compared with those without DM (Table 1). Ocular hypertension was relatively uncommon with only 5 individuals in the final analytical sample having the condition which prevents meaningful stratification by this variable. The mean value for visual field mean deviation was -2.11 decibels based on values measured on the better seeing eye of each subject.

The distribution of values of Humphrey Visual Field 24-2 mean deviation was roughly normal, allowing for analysis using t-test. Mean deviation of the better eye on Humphrey Visual Field 24-2 was not significantly different between those who had DM (-2.03dB, 95% CI -3.36, -0.70) and those without a diagnosis of DM (-2.16 dB, 95% CI -3.31, -1.00) on a two-tailed t-test (p=0.89). Power calculation for the sample size was low (0.2).

TABLE 1. Descriptive statistics for 102 individuals identified as having optic disc drusen and having completed at least 2 Humphrey 24-2 Visual Fields without other identifiable pathology.

Examination of the types of visual field defects in each eye of individuals in the final sample indicated 27% of eyes (n=55) had no specific pattern identifiable (Table 2). Of those with classifiable visual field defects, the most frequent type was arcuate or partial arcuate defect (42.6%, n=87) followed by nasal step (14.2%, n=29). There was no statistically significant difference between those with DM and those without (p=0.70).

Visual acuity in the better seeing eye was 20/30 or better in 97.1% (n=99) individuals. Three individuals in our final sample had visual acuity measuring 20/40 or worse in the better seeing eye limiting our ability to meaningfully compare visual acuity outcomes between groups. 

TABLE 2. Frequency of types of classifiable Visual field defects in either eye of individuals in the final analytic sample of 102 (204 eyes) veterans. Differences between DM and non-DM are not significant (p=0.70)

DISCUSSION

This study assessed whether diabetes is associated with worse visual function among individuals who have ODD. Visual function was determined by visual acuity, visual field mean deviation, and type of visual field defect. Among the 91,811 unique patients seen for eye care at the Veterans Affairs Portland Health Care System during the 7-year study period, 0.4% of patients were found to have ODD. This result is consistent with other published data, with prevalence ranges from 0.34%-2%.⁹ However, the prevalence depends on the definition of ODD and detection methods used. While visible ODD requires no confirmatory testing, the identification of buried drusen often requires additional diagnostic testing and may vary based on available technologies and clinician preference. Historically, ultrasonography was considered the gold standard due to its high sensitivity for diagnosis of both visible and buried ODD.¹⁰ There has been a shift toward optical coherence tomography with enhanced depth imaging that has demonstrated higher diagnostic precision and is a more readily available instrument.¹¹ In the chart review of the initial 485 records of this study, the confirmation of a diagnosis of ODD failed in 21.4%. This highlights the difficulty of definitively diagnosing the condition, even with frequent use of optical coherence tomography.

Visual impairment from ODD is usually mild, but in rare cases, severe vision loss is possible. In this study, 84.3% of patients retained normal vision (20/30 or better), similar to previous studies reporting a 72.4-98% retention of normal vision.¹² Results were similar regardless of a diagnosis of DM. Of those who did not retain normal vision, only 3 people had acuity 20/40 or worse with none who were legally blind.

Visual field defects from disc drusen are more common than reduced acuity, however, the exact mechanism is unknown. Proposed mechanisms include calcified bodies causing axonal degeneration of retinal ganglion cells via compression or vascular compromise, impaired axonal transport in eyes with small scleral canals resulting in gradual atrophy of optic nerve fibers or abnormal axonal metabolism due to accumulation of degraded or calcified mitochondria.^9,13,14 In this study, 72.5% of patients had visual field defects, which falls in the higher end of previous reports (11.2-87%).^13,15 The most frequent pattern of visual field defect in our study was an arcuate or partial arcuate defect occurring in 42.6% of eyes.

Diabetes was targeted due to its known association with vision loss and effect on visual field sensitivity, but also due to the prevalence of diabetes in the US population.^5,16–19 We hypothesized  that individuals with DM might display worse visual field sensitivity or more frequent defects compared with those without DM since diabetes is known to affect optic nerve head perfusion and peripapillary retinal nerve fiber layer thickness in preclinical diabetic retinopathy patients.²⁰  This was not the case in our analysis. There was no statistically significant difference in visual field mean deviation between those with DM and those without. However, results of a power analysis indicated that the sample size of this study was too small to be confident in the failure to reject the null hypothesis. Nonetheless, the difference in mean deviation between the two groups was too small to be clinically significant even if it were statistically significant. There was no statistically significant difference in type of visual field defect in those with DM compared with those without. These findings could be due to the restrictive exclusion criteria and low number of records in the final analysis compared with other studies. Additionally, because the focus of this study was on the role of systemic disease and visual function, only measurements of visual function for the better seeing eye were included, not taking into account the level of diabetic retinopathy in each eye.

A major limitation of this study is that it is a single site study with small sample size, which serves a predominantly elderly, white, male veteran population; these findings may not be applicable to the general population. Additionally, this study relied on ICD codes for initial identification of potential subjects. Although subjects were screened for incorrectly coded diagnoses and excluded, it is possible that not all patients with ODD were identified as such based on ICD coding which could result in an underestimation of the condition in our population.

CONCLUSION

Optic disc drusen is a well-known, sight-threatening condition while diabetes mellitus is a common systemic condition in the US. There is currently no evidence-based guidance on treatment and management of optic disc drusen, so clinicians are left to determine appropriate follow-up intervals based on a variety of considerations for each individual patient. The findings of our study would suggest that individuals with optic disc drusen and diabetes are unlikely to need more frequent follow-up than those without diabetes. A longitudinal study of individuals with optic disc drusen may provide more robust guidance in the future.

REFERENCES

1. Lam BL, Morais CG Jr, Pasol J. Drusen of the optic disc. Curr Neurol Neurosci Rep. 2008 Sep;8(5):404-8. doi: 10.1007/s11910-008-0062-6. PMID: 18713576.
2. Biçer Ö, Atilla H. Microvascular Changes Associated with Optic Disc Drusen: Case Report. Turk J Ophthalmol. 2019 Oct 24;49(5):300-304. doi: 10.4274/tjo.galenos.2019.14194. PMID: 31650815; PMCID: PMC6823588.
3. Zeiter JH, Shin DH, Baek NH. Visual field defects in diabetic patients with primary open-angle glaucoma. Am J Ophthalmol. 1991 May 15;111(5):581-4. doi: 10.1016/s0002-9394(14)73702-x. PMID: 2021166.
4. Keltner JL, Johnson CA, Cello KE, Edwards MA, Bandermann SE, Kass MA, Gordon MO; Ocular Hypertension Treatment Study Group. Classification of visual field abnormalities in the ocular hypertension treatment study. Arch Ophthalmol. 2003 May;121(5):643-50. doi: 10.1001/archopht.121.5.643. Erratum in: Arch Ophthalmol. 2008 Apr;126(4):561. PMID: 12742841.
5. Miller DR, Safford MM, Pogach LM. Who has diabetes? Best estimates of diabetes prevalence in the Department of Veterans Affairs based on computerized patient data. Diabetes Care. 2004 May;27 Suppl 2:B10-21. doi: 10.2337/diacare.27.suppl_2.b10. PMID: 15113777.
6. Jackson M, Becerra BJ, Marmolejo C, Avina RM, Henley N, Becerra MB. Prevalence and Correlates of Sleep Apnea Among US Male Veterans, 2005-2014. Prev Chronic Dis. 2017 Jun 15;14:E47. doi: 10.5888/pcd14.160365. PMID: 28617665; PMCID: PMC5477780.
7. Altalib HH, Fenton BT, Sico J, Goulet JL, Bathulapalli H, Mohammad A, Kulas J, Driscoll M, Dziura J, Mattocks K, Kerns R, Brandt C, Haskell S. Increase in migraine diagnoses and guideline-concordant treatment in veterans, 2004-2012. Cephalalgia. 2017 Jan;37(1):3-10. doi: 10.1177/0333102416631959. Epub 2016 Sep 30. PMID: 26950804.
8. Steinman MA, Lee SJ, John Boscardin W, Miao Y, Fung KZ, Moore KL, Schwartz JB. Patterns of multimorbidity in elderly veterans. J Am Geriatr Soc. 2012 Oct;60(10):1872-80. doi: 10.1111/j.1532-5415.2012.04158.x. Epub 2012 Oct 4. PMID: 23035702; PMCID: PMC4133992.
9. Palmer E, Gale J, Crowston JG, Wells AP. Optic Nerve Head Drusen: An Update. Neuroophthalmology. 2018 Apr 25;42(6):367-384. doi: 10.1080/01658107.2018.1444060. PMID: 30524490; PMCID: PMC6276953.
10. Malmqvist L, Bursztyn L, Costello F, Digre K, Fraser JA, Fraser C, Katz B, Lawlor M, Petzold A, Sibony P, Warner J, Wegener M, Wong S, Hamann S. The Optic Disc Drusen Studies Consortium Recommendations for Diagnosis of Optic Disc Drusen Using Optical Coherence Tomography. J Neuroophthalmol. 2018 Sep;38(3):299-307. doi: 10.1097/WNO.0000000000000585. PMID: 29095768.
11. Merchant KY, Su D, Park SC, Qayum S, Banik R, Liebmann JM, Ritch R. Enhanced depth imaging optical coherence tomography of optic nerve head drusen. Ophthalmology. 2013 Jul;120(7):1409-14. doi: 10.1016/j.ophtha.2012.12.035. Epub 2013 Mar 24. PMID: 23531353.
12. Lorentzen SE. Drusen of the optic disk. A clinical and genetic study. Acta Ophthalmol (Copenh). 1966:Suppl 90:1-180. PMID: 6012937.
13. Hamann S, Malmqvist L, Costello F. Optic disc drusen: understanding an old problem from a new perspective. Acta Ophthalmol. 2018 Nov;96(7):673-684. doi: 10.1111/aos.13748. Epub 2018 Apr 16. PMID: 29659172.
14. Auw-Haedrich C, Staubach F, Witschel H. Optic disk drusen. Surv Ophthalmol. 2002 Nov-Dec;47(6):515-32. doi: 10.1016/s0039-6257(02)00357-0. PMID: 12504737.
15. Lee JY, Park KA, Oh SY. Prevalence and incidence of non-arteritic anterior ischaemic optic neuropathy in South Korea: a nationwide population-based study. Br J Ophthalmol. 2018 Jul;102(7):936-941. doi: 10.1136/bjophthalmol-2017-311140. Epub 2017 Sep 28. PMID: 28972024.
16. Trick GL, Trick LR, Kilo C. Visual field defects in patients with insulin-dependent and noninsulin-dependent diabetes. Ophthalmology. 1990 Apr;97(4):475-82. doi: 10.1016/s0161-6420(90)32557-5. PMID: 2326027.
17. Bengtsson B, Heijl A, Agardh E. Visual fields correlate better than visual acuity to severity of diabetic retinopathy. Diabetologia. 2005 Dec;48(12):2494-500. doi: 10.1007/s00125-005-0001-x. Epub 2005 Nov 1. PMID: 16261313.
18. Parravano M, Oddone F, Mineo D, Centofanti M, Borboni P, Lauro R, Tanga L, Manni G. The role of Humphrey Matrix testing in the early diagnosis of retinopathy in type 1 diabetes. Br J Ophthalmol. 2008 Dec;92(12):1656-60. doi: 10.1136/bjo.2008.143057. Epub 2008 Oct 1. PMID: 18829632.
19. Jackson GR, Scott IU, Quillen DA, Walter LE, Gardner TW. Inner retinal visual dysfunction is a sensitive marker of non-proliferative diabetic retinopathy. Br J Ophthalmol. 2012 May;96(5):699-703. doi: 10.1136/bjophthalmol-2011-300467. Epub 2011 Dec 15. PMID: 22174096.
20. Cao D, Yang D, Yu H, Xie J, Zeng Y, Wang J, Zhang L. Optic nerve head perfusion changes preceding peripapillary retinal nerve fibre layer thinning in preclinical diabetic retinopathy. Clin Exp Ophthalmol. 2019 Mar;47(2):219-225. doi: 10.1111/ceo.13390. Epub 2018 Nov 13. PMID: 30203562.

Rebecca Czerwinski, OD, FAAO

Portland VA Health Care System | Portland, OR

Dr. Rebecca Czerwinski earned her Doctor of Optometry degree from Pacific University in 2002 and went on to complete a residency in Primary Care Optometry at Portland VA from 2002-2003. She then spent 4 years working in a co-management setting in a private practice, returning to the Portland VA as full-time staff since 2008. During her tenure, Dr. Czerwinski has served as Student Program Supervisor, VISN 20 Grand Rounds coordinator, member of the NAVAO membership committee, and oversaw the opening of the Bend Community Based Outpatient clinic while establishing the student externship there.

Molly S. Phan, OD, MPH, FAAO

VA Portland HCS | Portland, OR

Dr. Molly Phan earned her Doctor of Optometry Degree from University of Houston in 2004 and completed a residency in Primary Care Optometry at Portland VA from 2004-2005 where she now serves as Chief of the Optometry Section. She previously served on the Oregon Board of Optometry including two years as President of the Board and completed a Master of Public Health in Epidemiology from Oregon Health and Science University in 2023.

Amara Callahan, OD

Portland VA Medical Center, Vancouver Division | Vancouver, WA

Dr. Callahan graduated from Pacific University College of Optometry and is a staff optometrist and student supervisor at the Vancouver Division of the Portland VA Medical Center. She enjoys baking, traveling and paddle boarding with her husband and two daughters.

Grace L. Tsan, OD, FAAO

VA Portland Health Care System | Portland, Oregon

Grace L. Tsan, OD, FAAO is the Assistant Chief of Optometry at the VA Health Care System, Portland, OR. She is board certified by the American Board of Certification in Medical Optometry. Her areas of research interest include, but are not limited to, glaucoma, ocular syphilis, and central serous chorioretinopathy.

Vincent Chan, OD, ABCMO

Portland VA Healthcare System, Salem CBOC | Salem, OR

Dr. Chan, a graduate of the University of California, Berkeley's optometry program, honed his expertise through a residency in primary care and ocular disease at the Portland VA Medical Center. His commitment to veterans' eye health led him to join the Jonathan M. Wainwright Medical Center in Walla Walla, Washington, before transitioning to his current role as a staff optometrist at the Salem Community Based Outpatient Clinic of the Portland VA Medical Center. Dr. Chan's comprehensive background and dedication to patient care make him a valuable contributor to the field of medical optometry.​​​​​​​​​​​​​​​​

Kimberly Winges, MD

VA Portland Health Care System, Casey Eye Institute | Portland, OR

Dr. Kimberly Winges is a neuro-ophthalmologist who practices comprehensive/cataract surgery and neuro-ophthalmology at the VA Portland Health Care System, serves as the Assistant Chief of Surgery at the VA, and is Associate Professor of Ophthalmology and Neurology at the Casey Eye Institute, Oregon Health & Science University.

Christina Kim, OD

Scott Hyver Vision Care | San Jose, CA

Dr. Kim graduated from the University of California, Berkeley School of Optometry in 2019. She completed a primary care and ocular disease residency at VA Portland Health Care System. She now has returned to the Bay Area where she provides refractive eye care.

Michelle Lising, OD, FAAO

Kaiser Permanente Medical Center | Riverside, CA

Dr. Lising graduated from Southern California College of Optometry at Marshall B. Ketchum University in 2019 and completed a primary care/ocular disease residency at the VA Portland Healthcare System in Portland, OR. She is a fellow of the American Academy of Optometry.

Allison Mina Choi

Alcon | Fort Worth, TX

Dr. Choi attended Berkeley Optometry followed by a residency in primary care/ocular disease at the Portland VA. She worked in private practice for a few years before joining Alcon’s medical affairs team. She is a Fellow of the American Academy of Optometry.

Chau Bui, OD

NW Permanante | Portland, OR

Chau Bui graduated from UC Berkeley School of Optometry and completed her residency at the Salem VA Clinic.