5.2 Ocular Pathology & Systemic Disease

The Optician's Role: Recognize and Refer

Opticians do not diagnose or treat disease, but the ABO Advanced exam expects you to recognize the common conditions, understand how each alters vision and the prescription, and know when to refer. A sudden, unexplained change in acuity or an unusual complaint is a signal to send the patient back to the doctor rather than simply dispensing a stronger pair of glasses.

Diseases of the Lens, Angle, and Retina

Cataract is opacification (clouding) of the crystalline lens, most often age-related, that reduces acuity, contrast sensitivity, and color perception and causes glare, especially at night. A classic clue is a myopic shift (sometimes called second sight) as the lens changes index; a large, unexplained plus-to-minus change late in life warrants referral. Treatment is surgical removal with an intraocular lens (IOL); the patient becomes pseudophakic and needs UV protection.

Glaucoma is a group of optic neuropathies, frequently associated with elevated intraocular pressure (IOP), that damages the optic nerve and destroys peripheral vision first, progressing toward tunnel vision. Because painless side-vision loss goes unnoticed, a patient reporting field loss must be referred. It is managed with pressure-lowering drops, laser, or surgery.

Age-related macular degeneration (AMD) destroys central vision while sparing the periphery - the reverse of glaucoma. Dry (atrophic) AMD progresses slowly with drusen; wet (neovascular) AMD leaks and scars quickly and is a referral emergency. Patients report a central blur or a distorted or missing spot (scotoma); wavy lines (metamorphopsia) on an Amsler grid are a warning sign. These patients are prime candidates for near magnification aids.

Diabetic retinopathy is microvascular damage from chronic hyperglycemia: non-proliferative disease shows microaneurysms, dot-blot hemorrhages, and exudates, while proliferative disease grows fragile new vessels (neovascularization) that can bleed or detach the retina. It is a leading cause of blindness in working-age adults. Fluctuating blood sugar shifts the refraction between visits, so new blur in a diabetic should prompt fundus evaluation before you dispense.

Diseases of the Ocular Surface and Cornea

Dry eye (keratoconjunctivitis sicca) results from poor tear quantity or quality and causes burning, grittiness, fluctuating vision, and paradoxical reflex tearing. It is extremely common and undermines contact-lens tolerance and satisfaction with anti-reflective coatings, because patients notice smears. Conjunctivitis (pink eye) is inflammation of the conjunctiva - viral (watery, highly contagious), bacterial (purulent discharge), or allergic (itchy, bilateral). An acute red eye with pain, discharge, or light sensitivity should not be fitted; refer.

Keratoconus is a progressive corneal ectasia in which the cornea thins and bulges into a cone, producing irregular astigmatism and myopia that spectacles cannot fully correct. Spectacle acuity lags the apparent Rx; management moves from soft toric to RGP or scleral lenses and on to corneal cross-linking or transplant as it advances.

Systemic Disease and the Eye

Many systemic conditions show up first in the eye. Diabetes mellitus causes retinopathy and fluctuating refraction with blood-sugar swings (often a transient hyperopic or myopic shift), plus higher cataract and glaucoma risk. Hypertension produces hypertensive retinopathy - arteriolar narrowing, arteriovenous (AV) nicking, flame hemorrhages, and cotton-wool spots - and raises the risk of retinal vascular occlusions. Thyroid disease, especially Graves' (thyroid eye) disease, causes proptosis (exophthalmos), lid retraction, and restrictive muscle changes that can produce diplopia; a bulging eye or new double vision warrants referral. Medications matter too: long-term corticosteroids promote cataract and raise IOP, and hydroxychloroquine (Plaquenil) can cause a maculopathy that requires screening.

Red-Flag Symptoms and Referral

The exam tests judgment: which complaints mean stop and refer rather than adjust the frame. Treat the following as red flags:

• Sudden vision loss, or a sudden shower of floaters and flashes (possible retinal detachment)
• A curtain or shadow across the field, or new central distortion on an Amsler grid
• Acute painful red eye with halos and nausea (possible angle-closure glaucoma)
• Sudden-onset diplopia or a new eye turn (possible neurological cause)
• A rapidly changing prescription with no clear optical explanation
• Proptosis, unequal pupils, or a newly drooping lid

The correct action is to document the finding and refer promptly to an ophthalmologist or optometrist; never mask a pathological change with a new lens.

Dispensing With Disease in Mind

Once a patient is under a doctor's care, disease knowledge still shapes good dispensing. The pseudophakic (post-cataract) patient no longer has a natural UV-filtering lens for the tasks the IOL does not cover, so recommend 100 percent UV protection and often an anti-reflective coating and a light absorptive tint to tame residual glare. Cataract and early AMD patients benefit from contrast-enhancing measures - amber or plum tints, AR coating, and good task lighting - even before magnifiers are needed. Diabetic and hypertensive patients should be reminded that fluctuating vision may reflect systemic control rather than a wrong Rx, so hold off on remaking lenses during an unstable period. A frequent exam trap is choosing to strengthen a prescription for a patient whose true problem is progressive disease; the correct answer in those scenarios is referral first, dispensing second.