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Young woman presents with near vision blur
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A 26-year-old Caucasian female presented to our clinic for evaluation with one of our colleagues. Her chief complaint at that exam was a recent onset of near vision blur only, which she felt was slightly worse in the right eye for several weeks. She described the blur as being constant with no fluctuations. In addition, she also stated she was not experiencing any headaches or double vision.
Her medical history revealed a recent urinary tract infection (that had been successfully treated with antibiotics prior to this initial appointment), pre-diabetes, anxiety, depression and polycystic ovary syndrome. She was not currently using any ocular medications, and her systemic medications were: hydroxyzine, fluoxetine, buspirone, lurasidone, metformin, drospirenone/ethinyl estradiol and benztropine. Her blood pressure was measured at 112/65 mm Hg with a heart rate of 73 beats per minute. Her remaining family medical and ocular history were unremarkable. Her current occupation was a full-time graduate student at a local university.
With her habitual glasses prescription, the patient’s visual acuities at this initial visit were: 20/20-2 OD, 20/20 OS and 20/15-3 OU at distance and 20/40 OD, 20/30 OS and 20/40 OU at near. Confrontation visual fields and extraocular motilities were unremarkable at that exam. Pupils were equal, round and reactive to light and accommodation with no afferent pupillary defect. However, enlarged pupil diameters were found in both eyes, changing from 7 mm to 6 mm in dim to bright illumination, respectively. Manifest refraction revealed a moderate myopic refractive error in both eyes with best corrected distance acuities of 20/20 OD, 20/20+1 OS and 20/15-1 OU. Near testing with fused cross cylinder (FCC) with this myopic prescription was abnormal with a lag of +1.75 D and near visual acuities of 20/30 OD and 20/25 OS through a +2.00 D near add over her manifest refraction.
Tonometry, anterior segment and posterior segment evaluations were otherwise within normal limits in both eyes. At this point, the diagnosis of visual disturbances with suspicion of accommodative dysfunction was given to the patient, and she was referred to our advanced care ocular disease department for further evaluation and testing.
At the follow-up exam 1 week later (where we took over management of the case), entering acuities were measured at 20/15-2 OD, 20/15-1 OS and 20/15-2 OU for distance, with near acuities of 20/25-3 OD, 20/20-1 OS and 20/20 OU through her updated spectacle correction.
Systemic medications reported at this visit were: fluoxetine, buspirone, lurasidone, metformin, drospirenone/ethinyl estradiol and benztropine. The patient reported that her primary care physician had discontinued her hydroxyzine 1 day prior and that she noted her near acuities were mildly improved since stopping that medication only 24 hours earlier. Near point of convergence was reduced at 5 cm/15 cm (break/recovery). Near testing with the FCC at this visit was measured with a normal lag of +0.75 D. Von Graefe phorias measured 1 prism diopter of exophoria at distance and 7 prism diopters of exophoria at near. Near base-in vergences were 10/20/18, and near base-out vergences were x/23/12. Amplitudes of accommodation were 6.00 D OD and 6.00 D OS with push-up method, and negative relative accommodation/positive relative accommodation testing was measured at +2.25 D and -0.75 D, respectively. The rest of the exam remained unchanged from her previous visit 1 week prior.
What’s your diagnosis?
See answer on the next page.
When an eye care physician is told they are seeing a patient whose only complaint is near vision blur, the diagnosis will typically fall into one of two categories depending on the age of the patient. If the patient is 40 years old or more, the diagnosis is often presbyopia or uncorrected refractive error. If the patient is younger than 40, especially if they are near pediatric age, the diagnosis then leans more toward binocular vision dysfunction or accommodative dysfunction such as accommodative insufficiency, convergence insufficiency or uncorrected refractive error. However, when the patient sitting in the chair is a 26-year-old graduate school student with no prior near vision complaints, finding the correct etiology to make the proper diagnosis may require further evaluation of the patient and his or her medical history.
Based upon the patient’s near testing results, we diagnosed accommodative insufficiency (AI) due to her low accommodative amplitudes of 6.00 D. Minimum accommodative amplitudes for her age should be approximately 8.50 D based on Hofstetter’s formula: Minimum amplitudes = 15 – ¼ (age). On first glance, the patient had a larger exophoric posture at near than distance, but her near base-out vergence ranges appeared to be large enough to compensate for a 7-prism diopter exophoric posture. Therefore, we rested comfortably on our diagnosis of AI. However, upon a deeper review of her medication list, it dawned on us that perhaps we were missing a pharmacologic component to her recent reduction in near vision.
Review of medications
When the patient presented for her initial exam with one of our colleagues, she was taking buspirone, lurasidone, metformin, drospirenone/ethinyl estradiol, fluoxetine, hydroxyzine and benztropine. On first glance, these medications may not seem to have ocular side effects, but with closer inspection of their known mechanisms of action, one can see the potential for ocular side effects of several medications this patient was taking, as shown in the accompanying table. Based upon our thorough second viewing of her medication list, we determined potential causative medications to be: buspirone, fluoxetine, hydroxyzine, benztropine and lurasidone.
Buspirone is an anxiolytic (non-benzodiazepine) that is used to treat conditions such as Huntington disease, autism, schizophrenia and generalized anxiety disorder. Fanciullacci and colleagues and Koudas and colleagues have found buspirone to cause miotic pupils, which could have some significance with the near triad involving miosis, accommodation and convergence. However, to our knowledge, no mention of buspirone causing a decrease in near findings exists in the literature; it is only mentioned that miosis is a possible side effect. Given the patient’s large pupil size and difficulty seeing at near, we ruled this out as a possible culprit for her visual symptoms. Additionally, she had been on this medication for 18 months prior without incident, so it seemed unlikely that this would suddenly cause vision issues 18 months later.
Fluoxetine, a selective serotonin reuptake inhibitor (SSRI), is used in the treatment of conditions such as major depressive disorder, posttraumatic stress disorder, autism, panic disorder, obsessive compulsive disorder and bipolar disorder. SSRIs have the inherent ability to increase sympathetic tone, therefore having the potential to cause mydriasis and angle closure in some cases. Wernicke discusses findings that suggest that blurry vision may be a side effect of fluoxetine but does not discuss if that side effect is limited to distance or near vision only. However, it is generally accepted that SSRIs can exacerbate ocular surface disease, which could cause reduction in both distance and near vision. Regardless, the patient reported being on fluoxetine for longer than 18 months (the specific start date of fluoxetine was unknown by patient). Given the length of time the patient had been taking these medications (buspirone and fluoxetine), if any near vision decrease were a side effect of either medication, the patient would likely have experienced them prior to presenting to our clinic more than 18 months later. Therefore, we felt these medications had negligible effects on her overall findings.
Hydroxyzine is a first-generation antihistamine medication with possible secondary anticholinergic effects that can be used to treat anxiety, allergies, nausea, vomiting, insomnia and other medical ailments. As hydroxyzine has the ability to block cholinergic receptors, downstream effects can occur with the eyes. Most notably, pupil mydriasis and cycloplegia can occur, leading to symptoms of reduced accommodative amplitudes and blurry vision at near, as noted in this particular case. Additionally, she had started this medication for about 6 to 8 weeks before her symptoms started. Therefore, we felt that this medication likely was playing at least a small role in this patient’s visual complaints.
Benztropine, an anticholinergic medication used to treat schizophrenia, dystonia and Parkinson’s disease, may sound like a familiar drug to the eye care physician. However, it is not actually used in eye care. This is because atropine, another anticholinergic medication, is often used in eye care to stabilize or immobilize the ciliary body, which reduces accommodation and can cause pupillary mydriasis. Because the two medications are in the same category of drugs, it seems likely that benztropine and atropine would have similar side effects concerning reducing accommodation. The patient reported being on benztropine for 6 to 8 weeks prior to her symptoms starting. In a discussion about benztropine, Thaler suggests the drug’s ability to cause a reduction of vision. However, he also notes this does not usually occur unless the patient is also taking an antipsychotic. Interestingly, our patient was also taking an antipsychotic, lurasidone. However, others have found the combination of anticholinergic and antipsychotic medications is not necessary for reduced vision but that benztropine alone could cause a significant decrease in near vision (Fraunfelder).
Lurasidone is an atypical anti-psychotic medication that currently has an unknown mechanism of action. However, there may be evidence that it blocks certain serotonin receptors and/or dopamine receptors (Latuda package insert). If that is the case, possible ocular effects could result in a reduction in sympathetic tone leading to possible miosis and increased accommodation. However, we are unaware of any studies specifically looking at ocular side effects secondary to lurasidone use at the time of this article. Regardless, those clinical findings (miosis, increased accommodation) were not in our patient, and the patient had been taking it for 18 months without incident, which would suggest it likely had no measurable effect, if any, on her vision.
Resolution
The patient ultimately moved away from the Memphis area shortly after her last appointment at our clinic, so a follow-up exam was unable to be completed. However, we were able to speak with her via a phone call about 1 month later. At this time, she relayed to us that immediately after her last visit with us, her primary care physician discontinued her benztropine medication, and within 2 days the patient noted a drastic improvement in her near vision. At 7 days post-discontinuation of her benztropine, her near vision was 100% back to normal.
So, in this patient’s case, we feel that polypharmacy caused her near vision complaints. Specifically, we feel the combination of her hydroxyzine and benztropine medications led to her accommodative insufficiency diagnosis due to their ability to cause both pupillary mydriasis and cycloplegia from their inherent anticholinergic effects. She has since continued on her previous medications of fluoxetine, buspirone, lurasidone, metformin, drospirenone/ethinyl estradiol with no further visual problems. Therefore, we do not feel that these continued medications were causing her original visual complaints.
It is important to note that we feel vision therapy would have been a great option for this patient had her symptoms continued despite rearrangement of her medications. However, given her drastic improvement in her symptoms with discontinuing two of her medications, we felt a vision therapy referral was unwarranted.
Patients can have trouble with near vision for several different reasons. When examining a younger individual who is complaining of a recent onset of near blur only, clinicians should keep drug-induced differentials in mind to assist with clinical decision-making and work closely with a patient’s primary care physician to find the best solution for the patient. This case serves as an important reminder to clinicians to brush up on their systemic pharmacology knowledge from time to time for possible ocular side effects, despite the fact that the medications were not prescribed by eye care providers in the first place.
- References:
- Conen S, et al. Psychopharmacol. 2013;doi:10.1007/s00213-013-3075-z.
- Costagliola C, et al. Curr Neuropharmacol. 2008;doi:10.2174/157015908787386104.
- Fanciullacci M, et al. Clin Pharmacol Ther. 1995;doi:10.1016/0009-9236(95)90161-2.
- Farre M, et al. Br J Clin Pharmacol. 2014;doi:10.1111/bcp.12421.
- Fraunfelder FT. Drug-Induced Ocular Side Effects and Drug Interactions, 7th ed. Philadelphia: Lea and Febiger. 1976:213-214.
- Koudas V, et al. Psychopharmacology (Berl). 2009;doi:10.1007/s00213-009-1508-5.
- Latuda (lurasidone) package insert, Sunovion. www.latuda.com/LatudaPrescribingInformation.pdf. Accessed: June 18, 2018.
- Prozac (fluoxetine) package insert, Sarafem. www.accessdata.fda.gov/drugsatfda_docs/label/2011/018936s091lbl.pdf. Accessed: June 18, 2018.
- Thaler JS. Am J Optom Physiol Opt. 1982;59(11):918-919.
- Wernicke JF. J Clin Psychiatry. 1985;46;59-67.
- For more information:
- Chris Borgman, OD, FAAO, is assistant professor at the Southern College of Optometry in Memphis. He can be reached at: cborgman@sco.edu.
- Eric Woodward, OD, practices Butte Family Eye Center in Montana. He can be reached at: drwoodward@buttefamilyeyecenter.com.
- Edited by Leo P. Semes, OD, FAAO, a Primary Care Optometry News Editorial Board Member and Professor Emeritus in the Department of Optometry and Vision Science at the University of Alabama at Birmingham. He can be reached at: leopsemes@gmail.com.
Disclosures: Neither Borgman, Semes nor Woodward reports any relevant financial disclosures.
