Ocular Causes of Visual Distortions

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Ocular causes of visual distortions

Corey J Rowland, Lawrence R Lee VISUAL DISTORTION is a common including their age, sex and race, should presentation in general practice. Patients be noted. A systemic history is important can find it challenging to convey the to highlight any co-existing risk factors, Background Patients with complaints of visual subjective nature of their visual distortions such as diabetes, hypertension and distortions may first present to their and often describe the changes as ‘blurred hypercholesterolaemia. A personal and general practitioners (GPs) for vision’ or ‘vision loss’. Metamorphopsia, family ocular history should be obtained. A assessment. Visual distortions can micropsia, macropsia, scotomas and social history, inclusive of smoking history, present in various forms, from blurred paracentral scotomas are all symptoms of is also relevant. A detailed medication images to aberrations of colour. It is visual function disturbance described in history is important as numerous important to clarify any complaints of various macular disorders.1 These visual medications are associated with visual distortion to uncover potentially vision- threatening pathology. This can be symptoms can often herald or precede an phenomena. Vasodilators such as erectile achieved through a directed history underlying maculopathy. Visual distortion dysfunction drugs (eg sildenafil) may and examination. secondary to macular haemorrhage result in cyanopsia, a distinctive bluish can lead to potentially irreversible loss tinge in vision. Vasodilators such as beta Objective of vision if not treated promptly. Visual blockers and anti-anginal medications The aim of this article is to provide a guide to clarifying complaints of visual distortion secondary to macular oedema are known to cause phenomena such distortions, outlining the common in central retinal vein occlusion (CRVO) as shimmering, halos or scintillations. ocular causes, with a focus on macular could indicate malignant hypertension, Systemic corticosteroids are associated pathologies. leading to stroke and other end-organ with central serous chorioretinopathy damage if left undiagnosed. Thus, visual (CSCR) and resultant visual distortions. Discussion Targeted clues in the cause of visual distortions should be clarified and not distortions can be obtained through a overlooked. It is through a comprehensive Nature of visual distortion directed history. Simple office-based assessment that a general practitioner Distortions in vision can be described examination techniques such as visual (GP) can identify red flags to potentially in terms of shape (metamorphopsia), acuity, the use of Amsler’s grid and sight-threatening or life-threatening size (micropsia or macropsia) and fundoscopy are useful to identify conditions and refer appropriately. This colour (dyschromatopsia), and possible pathology responsible for visual distortions. A basic assessment and article focuses on visual distortions aetiologies can be localised to the knowledge of macular pathologies can secondary to maculopathies and other orbit itself or to the occipital cortex. assist GPs’ appropriate assessment, ocular causes; however, it is important to Metamorphopsia is defined as a treatment and referral of patients who consider neurogenic causes in assessment. deviation of either vertical or horizontal present with visual distortions. lines in central vision as described by the patient, and commonly indicates History macular pathology.1 Patients may Obtaining a detailed history is important complain of typically straight objects, to elicit potential causes of visual such as doorways or window frames, distortions. A patient’s demographic, looking bent or twisted, or simply objects

‘changing shape’. Distortions can manifest in particular sectoral field changes, to test for a relative afferent pupil defect as objects appearing disproportionately months or years prior to central distortion (RAPD), whereby a dilatory response is large (macropsia) or small (micropsia). development can be a sign of retinal vein elicited because of a reduction in afferent Dyschromatopsia or colour aberrations can occlusion with subsequent CMO.1 impulses from the optic nerve. An RAPD is also be implicated, but generally indicate generally observed in optic nerve disease.2 optic nerve pathology. Hemeralopia (day Associated symptoms blindness) or nyctalopia (night blindness) Any associated symptoms should be Visual fields can indicate retinal dystrophies. It is noted. Weakness or numbness on Visual fields to confrontation can important to elicit the location of the one side of the body, diplopia, slurred help define whether the pathology is visual distortion. Is it a sectoral field speech, headaches, difficulty swallowing, neurological or retinal. Sitting directly change suggestive of detachment, optic word-finding problems and imbalance across from the patient, the GP occludes neuropathy or retinal vascular disease? Or should be evaluated to rule out a one eye at a time, mirroring the patient. is it a central or paracentral abnormality, neurological cause of visual distortions. The patient, looking directly ahead, should seen in maculopathies or glaucomatous indicate when a moving target (usually the disease? Has the patient’s ability to read GP’s finger) is seen being brought in from deteriorated because of sections of the page Examination the periphery in all four quadrants. The being missing or are they having issues Vital and other signs patient’s visual field is compared with the with face perception due to a darkened A patient’s vital signs should be taken. GP’s to assess for any abnormalities. central scotoma? Determining whether Systemic hypertension is particularly the visual disturbance is present in one important and may manifest as Colour vision eye (monocular) or both eyes (binocular) hypertensive retinopathy/neuropathy and Colour vision testing using Ishihara plates can also aid in localising the pathology. retinal vein occlusion (RVO), leading to helps differentiate neurogenic from A monocular disturbance suggests that macular oedema. It may also be pertinent non-neurogenic vision changes. Acquired the lesion is anterior to the optic chiasm to check blood sugar levels or to conduct dyschromatopsia can be seen with lesions (eg retina, optic nerve, cornea); in cardiovascular and/or neurological of the optic nerve, retina or the visual contrast, binocular disturbances are more examinations depending on the nature cortex. Cerebral dyschromatopsia caused likely to be neurological. Associated visual of the presentation. by lesions at the occipital–temporal lobe symptoms such as photopsia, floaters and junction is usually accompanied by other transient scintillating colours may indicate Visual acuity focal neurology, including homonymous aetiologies such as tears, detachments and Visual acuity testing should be performed visual field defects.1 ocular migraines, respectively. using a Snellen chart and with appropriate refractive correction (ie the patient should Amsler grid Onset, duration and evolution wear their glasses if that is usual), or The Amsler grid was the first functional of symptoms using a pinhole. This can be performed test proposed to evaluate visual distortions A transient visual obscuration such as using a handheld chart or conventional (Figure 1A).1 It has application in general that experienced in embolic phenomena charts positioned at three and six metres’ practice to discover the presence and (eg amaurosis fugax) is likely to require distance from the patient. If the patient is location of defects in the central field more urgent evaluation than a central unable to see any letters, evaluate whether of vision and can also be used for home visual distortion of 12 months’ duration. the patient can count fingers, observe monitoring by patients. Magnetised Onset, duration and evolution of symptoms hand movements or simply perceive light. Amsler grids can be ordered from the helps triage the urgency of referral. A Visual distortions are often coupled with Macular Disease Foundation Australia static, central distortion of longer duration impaired visual acuity. website and are accessible on various can be suggestive of maculopathies such device applications. The Amsler grid as chronic, dry, age-related macular Intraocular pressure allows for simple and rapid qualitative degeneration (AMD), macular hole, Various forms of tonometry exist to evaluation of alterations of visual function epiretinal membrane (ERM) and diabetic measure intraocular pressure. Rebound in the central 10 degrees around a fixation macular oedema (DMO). Conversely, a tonometry, such as iCare, is the most point. It consists of a black or white card rapidly worsening central distortion can prevalent portable device and uses a small on which vertical and horizontal parallel be indicative of wet AMD with choroidal plastic-tipped probe that bounces gently lines are drawn, subdivided every 5 mm to neovascular membrane (CNVM) or CRVO against the cornea to obtain a reading. form a 10 cm square. The Amsler grid can with insipient cystoid macular oedema be used with patients using the following (CMO). Associated history of previous Pupils instructions: visual distortions in a young middle-aged Pupils should be examined for size and • wear your reading glasses and hold the male can be strongly suggestive of CSCR. their direct and consensual responses. grid at reading distance (approximately A history of previous sudden visual loss, The ‘swinging light test’ can be employed 28–30 cm)

526 | AJGP VOL. 48, NO. 8, AUGUST 2019 © The Royal Australian College of General Practitioners 2019 OCULAR CAUSES OF VISUAL DISTORTIONS FOCUS | CLINICAL

• cover one eye optic disc can be subsequently located by Referral • focus on the black dot in the centre following the blood vessels. The retinal Acute visual distortions or sudden of the grid without moving your eye vessels can be assessed and the macula deterioration of vision warrant urgent • comment on whether there are any identified by looking temporally to the referral for ophthalmological evaluation. broken, wavy, distorted or missing areas1 optic disc. Fundoscopic abnormalities These could represent maculopathies such • repeat the process with the other eye. are summarised in Table 1. The PanOptic as wet AMD with CNVM or potentially Abnormalities can include the absence Ophthalmoscope is particularly useful in CRVO with CMO, requiring further of a central fixation point (central general practice as it allows a fundal view investigation and management. More scotoma), inability to perceive outer that is five times greater than that seen indolent, progressive visual distortions areas of the grid (arcuate scotoma), with a standard ophthalmoscope in an may indicate conditions such as macular an area of the grid that is missing undilated eye. hole, epiretinal membrane, diabetic (paracentral scotoma), or distortions macular oedema or worsening dry AMD, in which the lines appear curvy or requiring semi-urgent evaluation. It is wavy (metamorphopsia; Figures 1B, Differential diagnosis important that GPs employ their clinical 1C), which can be further described as The most common macular diseases acumen in the referral process. For lines ‘bending’ inwards (micropsia) or characterised functionally by visual example, if there is concomitant vital sign outwards (macropsia).3 distortions are included in Table 2. instability or focal neurologic symptoms Diagnosis can be made using imaging in conjunction with visual distortions, Fundoscopy modalities such as optical coherence referral to an emergency department may Fundoscopy is performed with the tomography and various fundus be warranted for a holistic work-up. If lights off or dimmed and the patient photography techniques. there is uncertainty about the aetiology in a seated position. Dilate the patient with tropicamide 1% in each eye if pupil examination is normal and acute angle Table 1. Fundoscopic abnormalities closure and trauma is not suspected. Red reflex Reduced red reflex in corneal scarring, cataract, vitreous haemorrhage, Dilation may take 15 minutes. Instruct asteroid hyalosis the patient to fixate on a precise area, such Optic disc Pallor, swelling (papilloedema), haemorrhage, gross cupping, as the corner of the room. While holding new disc vessels the ophthalmoscope, the GP should Vessels Arteriovenous nipping, venous congestion and beading, emboli, examine the patient’s left eye with their microaneurysms, haemorrhages, exudate, cotton wool spots, own left eye and the patient’s right eye new retinal vessels with their own right eye. The presence of Macula Drusen, exudates, haemorrhage, pigmentary changes a red reflex should be assessed, and the

A B C

Figure 1. Amsler grid examples a. Normal Amsler grid; b. Small scotoma below central fixation with surrounding metamorphopsia;c . Large scotoma encroaching central fixation with some metamorphopsia4 Figure reproduced from Broadway DC. Visual field testing for glaucoma – A practical guide. Community Eye Health 2012:25(79–80):66–70. Licence at https://creativecommons.org/licenses/by-nc/3.0/au/

in a general practice setting, where diagnostics are limited, it is prudent to refer for further evaluation by an optometrist or ophthalmologist.

Key points • Visual distortions can indicate a scope of macular pathologies, from benign to potentially sight-threatening. • A directed history and examination using office-based techniques including visual acuity, Amsler grid and fundoscopy are A B helpful in the initial assessment. • Urgency of ophthalmological evaluation is based on the nature of the presentation.

Authors Corey Rowland MBBS, Clinical Fellow, City Eye Centre, Brisbane, Qld Lawrence R Lee MBBS, FRANZCO, FRACS, Associate Professor, City Eye Centre, University of Queensland; Royal Brisbane & Women’s Hospital, Brisbane, Qld. [email protected] Competing interests: None. Funding: None. C D Provenance and peer review: Commissioned, externally reviewed.

References 1. Midena E, Vujosevic S. Metamorphopsia: An overlooked visual symptom. Ophthalmic Res 2016;55(1):26–36. doi: 10.1159/000441033. 2. Rahman S, Grewal DS, Bhat P, Fallor M, Volpe NJ, Mirza R. Relative afferent pupillary defect detected in asymmetric macular disease using an automated binocular pupillometer. Invest Ophthalmol Vis Sci 2014;55(13):1185. 3. Pandey AN, Raina A, Sharma PD. A study on Amsler’s Grid in acquired macular disorders. Ophthalmology Research: An International Journal 2016;6(3):1–7. doi: 10.9734/OR/2016/28850. 4. Broadway DC. Visual field testing for glaucoma – A practical guide. Community Eye Health E F 2012:25(79–80):66–70. 5. Al-Zamil WM, Yassin SA. Recent developments in age-related macular degeneration: A review. Clin Figure 2. a. Fundus photo and optical Interv Aging 2017;12:1313–30. doi: 10.2147/CIA. coherence tomography (OCT) of drusen in S143508. early dry age-related macular degeneration 6. Smith W, Assink J, Klein R, et al. Risk factors (AMD); b. Fundus photo and OCT of choroidal for age-related macular degeneration: Pooled neovascular membrane in wet AMD with retinal findings from three continents. Ophthalmology haemorrhage; c. Fundus photo and OCT of 2001;108(4):697–704. full-thickness macular hole; d. Fundus photo 7. Chakravarthy U, Wong TY, Fletcher A, et al. and OCT of central serous chorioretinopathy Clinical risk factors for age-related macular with subretinal fluid;e . Fundus photo and degeneration: A systematic review and meta- OCT of branch retinal vein occlusion with analysis. BMC Ophthalmol 2010;13;10:31. doi: 10.1186/1471-2415-10-31. cystoid macular oedema (CMO); f. Fundus photo of proliferative diabetic retinopathy with 8. Parekh N, Voland RP, Moeller SM, et al. Association between dietary fat intake and age- new blood vessel formation and panretinal related macular degeneration in the Carotenoids photocoagulation scars; OCT features diabetic in Age-Related Eye Disease Study (CAREDS): macular oedema; g. Fundus photo and OCT of An ancillary study of the women’s health G epiretinal membrane with secondary CMO initiative. Arch Ophthalmol 2009;127(11):1483–93. doi: 10.1001/archophthalmol.2009.130.

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Table 2. Common maculopathies causing visual distortions

Retinal vein Diabetic occlusion (RVO) retinopathy with Age-related macular Central serous with cystoid diabetic macular Vitreomacular Maculopathy degeneration (AMD) Macular holes chorioretinopathy macular oedema oedema interface disorders

Definition Acquired disease A retinal break Characterised by Retinal vein Diabetic disease Vitreomacular characterised by commonly accumulation of occlusive disease leading to interface neurodegeneration of the involving the subretinal fluid, leading to accumulation of fluid abnormalities photoreceptor–retinal fovea12 commonly under the complications of in the macula19 inclusive of pigment epithelial macula15 interrupted blood adhesions, traction complex5 flow including and membranes21 macular swelling17

Types • Dry (non-exudative) • Full-thickness • Acute • Branch retinal • Non-proliferative • Vitreomacular • Wet (exudative) • Partial-thickness • Chronic vein occlusion diabetic traction (VMT) (lamellar holes) • Central retinal retinopathy • Epiretinal vein occlusion • Proliferative membrane (ERM) diabetic retinopathy

Risk factors • Increasing age • Age • Age • Systemic arterial • Duration of • Age • Ethnicity • Female sex • Male sex hypertension diabetes • Retinal vascular • Genetics • Myopia • Corticosteroid • Atherosclerosis • Proteinuria disease • Smoking • Trauma exposure • Diabetes • Sex • Diabetes • High intake of saturated • Ocular • Phosphodiesterase • Thrombophilia • Cardiovascular • Trauma and trans fats and inflammation13 inhibitor use • Glaucoma disease • Inflammatory omega-6 fatty acids • Obstructive sleep • Sleep apnoea • High glycated conditions • Abdominal obesity apnoea • Homocystinuria17 haemoglobin • Tumours • Hyperlipidaemia • ‘Type A’ personality levels • Retinal 16 19 • Hyperopia traits • Diuretic use dystrophies21 • Light iris colour • Cardiovascular disease • Hormonal status • Alcohol use • Vitamin B and D status • Elevated C-reactive protein6–8

Symptoms • Reduced vision • Reduced vision • Reduced vision • Reduced vision • Reduced vision • Reduced vision • Visual distortions • Visual distortions • Visual distortions • Visual distortions • Visual distortions • Visual distortions

Clinical • Dry AMD: Drusen and • Well-defined • Well-demarcated • Vascular • Macular • VMT: Distortion features geographical atrophy round or round or oval- tortuosity thickening of the fovea, in advanced disease oval lesion in shaped area of • Retinal • Exudates and blunted foveal (Figure 2A) the macula neurosensory haemorrhages cystoid changes reflex, cystic • Wet AMD: Choroidal (Figure 2C) detachment with • Cotton wool • Microaneurysms macular changes, or without serous subretinal fluid neovascular membrane spots • Haemorrhage and PED (Figure 2B) PED (Figure 2D) • ERM: Reflective • Optic nerve • Hard exudates oedema sheen over retina, • Retinal wrinkling of • Macular oedema neovascularisation retinal surface (Figure 2E) (Figure 2F) (Figure 2G)

Treatment • Dry AMD: Preventative • Surgical repair • Spontaneous • Therapies • Intravitreal • VMT: Paras strategies; smoking with vitrectomy resolution of fluid targeted at injections, laser plana vitrectomy; prevention; daily dose with or without by three months; complications of photocoagulation pharmacologic of vitamin C, vitamin E, internal limiting potential therapies RVO; intravitreal and vitreous vitreolysis with lutein, zeaxanthin, zinc membrane include focal laser anti-VEGF surgery20 ocriplasmin oxide and cupric oxide9 peel and gas photocoagulation, therapy, grid laser • ERM: Pars plana • Wet AMD: Intravitreal tamponade; photodynamic and intravitreal vitrectomy with anti-VEGF injections, post-operative therapy and steroids18 membrane peel21 such as ranibizumab, posturing intravitreal bevacizumab and required14 anti-VEGF aflibercept10,11 medications16

PED, pigment epithelial detachment; VEGF; vascular endothelial growth factor

9. Age-Related Eye Disease Study 2 Research 18. Ip M, Hendrick A. Retinal vein occlusion review. Group. Lutein + zeaxanthin and omega-3 Asia Pac J Ophthalmol (Phila) 2018;7(1):40–45. fatty acids for age-related macular doi: 10.22608/APO.2017442. degeneration: The Age-Related Eye Disease 19. Gundogan F, Yolcu U, Akay F, Ilhan A, Ozge G, Study 2 (AREDS2) randomized clinical trial. Uzun S. Diabetic macular edema. Pak J Med Sci JAMA 2013;309(19):2005–15. doi: 10.1001/ 2016;32(2):505–10. doi: 10.12669/pjms.322.8496. jama.2013.4997. 20. Wang W, Lo ACY. Diabetic retinopathy: 10. Mantel I. Optimizing the anti-VEGF treatment Pathophysiology and treatments. Int J Mol Sci strategy for neovascular age-related macular 2018;19(6). pii: E1816. doi: 10.3390/ijms19061816. degeneration: From clinical trials to real-life 21. Levison AL, Kaise PK. Vitreomacular interface requirements. Transl Vis Sci Technol 2015;4(3):6. disease: Diagnosis and management. Taiwan 11. Park DH, Sun HJ, Lee SJ. A comparison J Ophthalmol 2014;4(2):63–68. doi: 10.1016/j. of responses to intravitreal bevacizumab, tjo.2013.12.001. ranibizumab, or aflibercept injections for neovascular age-related macular degeneration. Int Ophthalmol 2017;37(5):1205–14. doi: 10.1007/ s10792-016-0391-4. 12. Zhao PP, Wang S, Liu N, Shu ZM, Zhao JS. A review of surgical outcomes and advances for macular holes. J Ophthalmol 2018;2018:7389412. doi: 10.1155/2018/7389412. 13. La Cour M, Friis J. Macular holes: Classification, epidemiology, natural history and treatment. Acta Ophthalmol Scand 2002;80(6):579–87. 14. Dhawahir-Scala FE, Maino A, Saha K, Mokashi AA, McLauchlan R, Charles S. To posture or not to posture after macular hole surgery. Retina 2008;28(1):60–65. doi: 10.1097/ IAE.0b013e31813c68a2. 15. Wang M, Munch IC, Hasler PW, Prünte C, Larsen M. Central serous chorioretinopathy. Acta Ophthalmol 2008;86:126–45. 16. Ross A, Ross AH, Mohamed Q. Review and update of central serous chorioretinopathy. Curr Opin Ophthalmol 2011;22(3):166-73. doi: 10.1097/ ICU.0b013e3283459826. 17. Rogers SL, McIntosh RL, Lim L, et al. Natural history of branch retinal vein occlusion: An evidence-based systematic review. Ophthalmology 2010;117(6):1094–101.e5. doi: 10.1016/j. ophtha.2010.01.058. correspondence [email protected]