Patient History and Ophthalmic Examination Techniques Flashcards

During slit-lamp examination, a patient presents with a Krukenberg spindle on the corneal endothelium. Which historical finding would most strongly support a diagnosis of pigment dispersion syndrome rather than pseudoexfoliation syndrome?

Answer: Patient reports blurred vision after vigorous exercise or pupillary dilation

Pigment dispersion syndrome (PDS) classically causes transient blurring and halos after vigorous exercise or pharmacologic dilation due to mechanical rubbing of the iris pigment epithelium against the zonular fibers, releasing pigment. This distinguishes PDS from pseudoexfoliation syndrome, which does not produce exercise-induced visual symptoms. The other options are not characteristic of PDS.

When recording best-corrected visual acuity in a patient with nystagmus, the technician notes the patient achieves better acuity when the head is turned 20° to the left. What is the clinical significance of this null point, and how should the acuity be properly documented?

Answer: Document acuity in the null point position and note the compensatory head posture, as this represents the patient's functional best acuity

The null point is the gaze position where nystagmus amplitude and frequency are minimized, yielding the patient's best functional acuity. Proper documentation includes visual acuity measured in the null point position and notation of the compensatory head posture. Recording only primary-gaze acuity would underestimate the patient's true functional vision and misguide clinical management.

A 58-year-old patient taking tamsulosin (Flomax) for benign prostatic hyperplasia is scheduled for cataract surgery. Which specific historical detail must the technician proactively flag in the pre-operative assessment, and why is it time-sensitive?

Answer: Duration of tamsulosin use, because longer use increases the risk of posterior capsule rupture and the surgeon must plan accordingly before the day of surgery

Tamsulosin and other alpha-1 antagonists are strongly associated with Intraoperative Floppy Iris Syndrome (IFIS), characterized by a flaccid, billowing iris, progressive intraoperative miosis, and iris prolapse. The surgeon must be informed prior to surgery — ideally well before the operative date — to prepare modified instrumentation and pharmacologic strategies (e.g., iris hooks, Malyugin ring, intracameral phenylephrine). Even if the patient has stopped tamsulosin, the effect can persist indefinitely because of irreversible alpha-1 receptor changes in the iris dilator muscle.

A technician performs Goldmann applanation tonometry on a patient with a history of LASIK surgery. The pachymetry reads 490 µm centrally. The Goldmann reading is 14 mmHg. Which statement best describes the interpretation of this IOP measurement?

Answer: The reading likely underestimates true IOP because post-LASIK corneas are biomechanically weaker and the reduced stromal thickness decreases applanation resistance

Post-LASIK corneas have reduced central corneal thickness and altered biomechanical properties (decreased rigidity and corneal hysteresis). Goldmann applanation tonometry assumes a standard corneal thickness of 520 µm and normal biomechanics; thinner, more compliant post-LASIK corneas require less force to applanate, causing the instrument to underestimate true IOP. This is clinically significant in glaucoma suspects, where underestimated IOP may lead to delayed diagnosis or inadequate treatment. Correction formulas or alternative tonometry methods (e.g., dynamic contour tonometry) should be considered.

During confrontation visual field testing, a patient with a known right homonymous hemianopia fails to detect the examiner's finger in the right visual field of the left eye but detects it normally in the left visual field of the left eye. When testing the right eye, the same pattern is observed. What is this pattern called, and at what anatomical level does it localize the lesion?

Answer: Right homonymous hemianopia; lesion in the left optic tract, lateral geniculate nucleus, optic radiations, or occipital cortex posterior to the chiasm

A right homonymous hemianopia (loss of the right visual field in both eyes) localizes the lesion to the left retrochiasmal visual pathway — anywhere from the left optic tract through the left lateral geniculate nucleus, left optic radiations, or left occipital cortex. Lesions posterior to the chiasm produce contralateral homonymous field defects because the nasal fibers of the ipsilateral eye and temporal fibers of the contralateral eye have already crossed and reunited. The pattern described (right field loss in both eyes) is the defining feature of a left-sided retrochiasmal lesion.

When obtaining a medication history, a patient mentions long-term use of hydroxychloroquine (Plaquenil) for lupus. According to current screening guidelines, which examination finding on spectral-domain OCT would be the earliest reliable indicator of hydroxychloroquine toxicity, preceding subjective visual complaints?

Answer: Parafoveal thinning of the outer nuclear layer and photoreceptor ellipsoid zone loss on high-resolution macular OCT

Hydroxychloroquine toxicity characteristically causes parafoveal (not central foveal) loss of the outer retinal layers, specifically thinning of the outer nuclear layer and disruption of the photoreceptor ellipsoid zone (IS/OS junction), visible on spectral-domain OCT before visual symptoms or detectable fundus changes appear. This parafoveal 'flying saucer' pattern on en face OCT corresponds to the characteristic bull's-eye maculopathy seen in advanced toxicity. Current AAO guidelines (2016) recommend SD-OCT as the primary objective screening tool, as it detects subclinical toxicity years before patients notice visual loss.