Physical Examination Findings in Cataract During Eye Exam
The definitive physical exam finding for cataract is lens opacity visualized on slit-lamp biomicroscopy through a dilated pupil, which must be correlated with the patient's visual symptoms to establish clinical significance. 1
Core Examination Components
Essential Visual Function Testing
- Visual acuity testing at distance and near with current correction, documenting the power of present correction 1
- Refraction and corrected distance visual acuity (CDVA) measurement in both eyes 1
- Glare testing reveals disproportionate visual disability—patients may have normal or near-normal acuity in a darkened exam room but experience significant drops when tested with a glare source, particularly useful for cortical and posterior subcapsular cataracts 1, 2, 3
- Contrast sensitivity testing demonstrates functional vision loss not captured by Snellen acuity alone, showing reduced ability to detect subtle variations in shading 1, 2
Critical Slit-Lamp Biomicroscopy Findings
Slit-lamp examination through a dilated pupil is the gold standard for identifying lens opacities and determining their clinical significance. 1
The three main cataract types have distinct appearances:
- Nuclear cataracts: Central lens opacification or discoloration (brunescent or opalescent), progressing slowly and primarily affecting distance vision 4
- Cortical cataracts: Opaque spokes or oil droplets in the lens cortex (central or peripheral), commonly producing glare symptoms; when the entire cortex becomes white and opaque, termed mature cortical cataract 3, 4
- Posterior subcapsular cataracts (PSC): Located just inside the posterior lens capsule, causing substantial visual impairment when involving the axial region, with near vision typically more affected than distance due to miosis with accommodation 3, 4
Additional Required Examination Elements
- Pupil size and function assessment to evaluate for surgical planning considerations 1
- External examination of eyelids, lashes, lacrimal apparatus, and orbit 1
- Intraocular pressure measurement 1
- Examination of cornea, anterior chamber, iris, vitreous, macula, peripheral retina, and optic nerve through dilated pupil to rule out other causes of vision loss 1
- Indirect ophthalmoscopy for comprehensive posterior segment evaluation 1
- Visual field assessment 1
- Ocular alignment and motility examination 1
Key Clinical Pitfalls
Visual acuity alone severely underestimates functional impairment from cataracts—glare testing and contrast sensitivity provide critical additional information about real-world visual disability. 2, 3 A patient may read 20/40 on the Snellen chart but be unable to drive safely at night due to severe glare from cortical or PSC cataracts. 1, 3
Always rule out other causes of vision loss before attributing symptoms solely to cataracts. 2 Reduced visual acuity with glare testing is not specific for cataract and may result from ocular surface disease, requiring correlation with slit-lamp findings. 1
Supplemental Testing When Indicated
- Tear function assessment: Reduced tear meniscus, tear breakup time <10 seconds, debris in tear film, low Schirmer test scores, or punctate erosions indicate tear dysfunction that may compromise surgical outcomes 1
- Corneal topography/tomography: Useful when corneal irregularities may contribute to visual impairment or affect surgical planning 1, 2
- Specular microscopy and pachymetry: For patients with suspected corneal endothelial dysfunction from dystrophies, previous surgery, or trauma, though these have relatively low accuracy in predicting postoperative corneal clarity 1
Important Preoperative Considerations
Document use of systemic alpha-1 antagonists (e.g., tamsulosin) as these increase risk of intraoperative floppy iris syndrome. 2, 5 Some ophthalmologists temporarily discontinue these medications preoperatively. 5
Identify immunosuppressive conditions, diabetes, and other risk factors that can affect surgical planning or outcomes. 1