Brachy Eye (BOS) — Big Eyes Are Exposed Eyes

Big bulging eyes look cute — but they're also exposed and unprotected. About half of all flat-faced dogs have corneal damage by adulthood. Daily eye drops prevent 80% of problems. And if your Frenchie's eye ever pops out of socket — RUN to the ER.

I. What BOS Is

BOS = Brachycephalic Ocular Syndrome. Not one disease — a syndrome where shallow eye sockets, exposed corneas, large eyelid openings, incomplete blinking, and abnormal eyelashes all combine to chronically damage the ocular surface.

Sebbag et al. 2023 (Veterinary Ophthalmology) called it a "pandemic of ocular surface disease," driven by demand for flat-faced breeds.

II. The 9 Components of BOS

1. Shallow eye sockets (exophthalmia) — globe sits more exposed/forward, little bony protection
2. Macroblepharon — excessively wide eyelid opening
3. Lagophthalmos — incomplete blinking, especially during sleep
4. Pigmentary keratitis — brownish-black melanin on cornea from chronic irritation
5. Medial canthal entropion — inner corner eyelid rolls inward; nasal hairs/folds rub cornea
6. Trichiasis / distichiasis — abnormal eyelashes scrape cornea
7. Exposure keratitis / corneal ulceration
8. Tear film instability (qualitative dry eye — see KCS)
9. Proptosis risk — globe can pop out of socket from minor trauma

III. How Common — Sebbag 2023

Based on a sample of 93 brachycephalic dogs (38 of them Frenchies):

IV. Eye Injuries from Minor Trauma

Frenchie eyes protrude and don't have full blink protection. Everyday events cause damage:

• Swat from another dog or cat → corneal scratch
• Running through bush, branch, tall grass → ulcer
• Bedding fibers, hay, mulch → corneal abrasion
• Self-trauma when scratching face → ulcer
• Wind exposure on car rides → cornea dries enough to irritate

V. Daily Prevention — The Highest Leverage Habit

1. Lubricating artificial tears (preservative-free) 1-3× daily, every day for life — Hylo-Tears, GenTeal, I-Drop Vet Plus
2. Wipe inner corner with sterile saline pads daily — debris, mucus, irritants from skin folds
3. Examine eyes daily under good light — cloudy spots, redness, squinting, brown pigment
4. Hydrating eye gel at bedtime — combats overnight lagophthalmos
5. Avoid grass/branches at face height on walks
6. No rough play with eye-level hazards
7. Annual ophthalmology exam (not just GP) — ACVO recommends

VI. Surgery Options

• Medial canthoplasty — partial closure of inner eyelid corner. Gold-standard surgical fix for BOS. Reduces eye aperture, corrects medial entropion, improves tear distribution, removes nasal hairs from corneal contact.
• Standard entropion repair (Hotz-Celsus) — for lateral entropion only; success 90-95%
• Tarsorrhaphy — temporary partial eyelid suturing for proptosis recovery
• Conjunctival grafts — for deep ulcers
• Corneal grafting — for perforations or severe pigmentary keratitis

VII. Pigmentary Keratitis Treatment

• Topical cyclosporine 0.2% (Optimmune) — primary, slows progression
• Topical tacrolimus — more potent alternative
• Topical corticosteroids — only when no ulcer present (steroids worsen ulcers)
• Pigment usually does NOT regress fully — goal = STOP further progression
• Surgery (superficial keratectomy) for advanced vision-threatening cases — but pigment often returns

VIII. Proptosis Specifically

Approximately ≥72% of proptosed eyes lose vision even with surgery (only ~28% retain useful vision per Today's Veterinary Practice). Time-to-treatment is the biggest factor. Frenchies are among the highest-risk along with Pugs and Pekingese (shallow orbits).