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Iran Ophthalmology Specialty Board study materials
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Iran Ophthalmology Specialty Board practice questions

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Question 1Optics, Refraction and Contact Lenses

در یک چشم نرمال (اگزمتروپ) که تنها از عینک طبی با قدرت ‎+10.00 D‎ در فاصله رأس ۱۲ میلی‌متری استفاده می‌کند، بزرگ‌نمایی نسبی عینک تقریباً چقدر است؟

  1. حدود ۱٫۴۵ برابر
  2. حدود ۱٫۱۲ برابر Correct answer.
  3. حدود ۱٫۰۱ برابر
  4. حدود ۰٫۸۹ برابر

Explanation

بزرگ‌نمایی عینک برای چشم اگزمتروپ برابر نسبت فاصله کانونی چشم به فاصله کانونی مؤثر عینک است، یعنی ‎1/(1-dF)‎. با ‎F=+10‎ و ‎d=0.012‎ مقدار مخرج ‎0.88‎ می‌شود و بزرگ‌نمایی حدود ۱٫۱۲ به‌دست می‌آید. عدسی محدب همیشه بزرگ‌نمایی مثبت و بزرگ‌تر از یک ایجاد می‌کند.

Question 2Optics, Refraction and Contact Lenses

در کراتومتری، اختلاف قدرت قرنیه در دو نصف‌النهار عمود بر هم ۳٫۵ دیوپتر است. این یافته بیانگر کدام وضعیت است؟

  1. کراتوکونوس تحت بالینی
  2. آستیگماتیسم قرنیه‌ای منظم Correct answer.
  3. آستیگماتیسم قرنیه‌ای نامنظم
  4. قوزقرنیه قطعی

Explanation

آستیگماتیسم منظم زمانی مطرح می‌شود که دو نصف‌النهار اصلی عمود بر هم باشند و اختلاف قدرت داشته باشند؛ اختلاف ۳٫۵ دیوپتر در کراتومتری کلاسیک با آستیگماتیسم منظم قرنیه‌ای سازگار است. نامنظمی به معنای نبود عمود بودن یا نبود تقارن محورها است که با کراتومتری ساده قابل تأیید نیست.

Question 3Optics, Refraction and Contact Lenses

بیماری با میوپی ‎-8.00 D‎ می‌خواهد از لنز تماسی نرم استفاده کند. کدام گزینه درباره تبدیل قدرت عینک به لنز تماسی درست است؟

  1. قدرت لنز تماسی باید کمتر منفی از قدرت عینک باشد. Correct answer.
  2. قدرت لنز تماسی دقیقاً برابر قدرت عینک است.
  3. قدرت لنز تماسی مستقل از فاصله رأس است.
  4. قدرت لنز تماسی باید منفی‌تر از قدرت عینک باشد.

Explanation

در نزدیک‌کردن عدسی منفی به چشم، فاصله کانونی مؤثر کاهش می‌یابد و برای حفظ همان نقطه دور، قدرت منفی کمتری لازم است. بنابراین لنز تماسی برای میوپی بالا عددی کمتر منفی از عینک خواهد داشت. این اصل با فرمول ‎Fc=F/(1-dF)‎ قابل محاسبه است.

Question 4Optics, Refraction and Contact Lenses

کدام پدیده بهترین توضیح برای کاهش حساسیت کانتراست در بیماران با لنز تماسی نرم سیلیکون‌هیدروژل با کمبود اکسیژن رسانی مزمن است؟

  1. کاهش تولید اشک بازال
  2. افزایش ادم اپیتلیال و تغییرات ناشی از هیپوکسی Correct answer.
  3. افزایش حساسیت قرنیه
  4. افزایش تعداد سلول‌های گابلت ملتحمه

Explanation

کمبود اکسیژن مزمن باعث ادم اپیتلیال و تغییرات متابولیک قرنیه می‌شود که پراکندگی نور و کاهش حساسیت کانتراست را به همراه دارد. این تغییرات با انتخاب لنز با نفوذپذیری اکسیژن کافی قابل پیشگیری است.

Question 5Optics, Refraction and Contact Lenses

برای اصلاح آستیگماتیسم نامنظم پس از پیوند قرنیه، کدام روش تصحیح نوری بیشترین شانس بهبود دید را دارد؟

  1. لنز تماسی نرم توریک
  2. لنز تماسی سخت گازی نافذ Correct answer.
  3. لنز تماسی نرم کروی
  4. عینک استوانه‌ای ساده

Explanation

در آستیگماتیسم نامنظم، سطح قرنیه دارای نواحی با قدرت‌های متفاوت و نامتقارن است و عدسی‌های سخت با ایجاد لایه اشک اشکی منظم، سطح نوری جدید و منظمی می‌سازند. لنزهای نرم با سطح نامنظم قرنیه تطابق یافته و بی‌نظمی را اصلاح نمی‌کنند.

Question 6Optics, Refraction and Contact Lenses

در آزمون رتینوسکوپی استاتیک، اگر با حرکت آینه نور در جهت موافق حرکت لکه مشاهده شود، چه نتیجه‌ای گرفته می‌شود؟

  1. آستیگماتیسم نامنظم
  2. نقطه خنثی دقیقاً روی چشم
  3. خطای انکساری با علامت منفی (میوپی)
  4. خطای انکساری با علامت مثبت (هیپروپی) Correct answer.

Explanation

در رتینوسکوپی با آینه صفحه‌ای، حرکت موافق لکه با حرکت آینه نشان‌دهنده بازتاب در حالت دور از خنثی و معمولاً خطای هیپروپیک است. برای رسیدن به خنثی باید عدسی محدب اضافه کرد.

Question 7Optics, Refraction and Contact Lenses

بیماری با افزودن ‎+2.50 D‎ برای دید نزدیک، در فاصله کاری ۴۰ سانتی‌متر دچار خستگی است. کدام تغییر منطقی‌تر است؟

  1. حذف کامل افزودن
  2. افزایش فاصله کاری به ۶۰ سانتی‌متر
  3. کاهش افزودن به ‎+1.50 D‎ Correct answer.
  4. افزایش افزودن به ‎+3.50 D‎

Explanation

افزودن ‎+2.50 D‎ معادل فاصله کاری ۴۰ سانتی‌متر است و اگر بیمار در همین فاصله خستگی دارد، احتمال بیش‌تصحیح یا نیاز کمتر به افزودن وجود دارد. کاهش افزودن به ‎+1.50 D‎ فاصله کاری را دورتر می‌برد و بار تطابقی را کم می‌کند.

Question 8Optics, Refraction and Contact Lenses

کدام شاخص در توپوگرافی قرنیه بیشترین حساسیت را برای شناسایی قوزقرنیه تحت بالینی دارد؟

  1. شاخص عدم تقارن سطح خلفی Correct answer.
  2. شاخص قطر مردمک
  3. شاخص ضخامت مرکزی
  4. شاخص عدم تقارن سطح قدامی

Explanation

تغییرات سطح خلفی قرنیه در قوزقرنیه زودتر از سطح قدامی ظاهر می‌شود و شاخص عدم تقارن خلفی حساسیت بالایی برای شناسایی موارد تحت بالینی دارد. توپوگرافی مبتنی بر ارتفاع خلفی از آزمون‌های تکمیلی کلیدی است.

Question 9Optics, Refraction and Contact Lenses

برای بیمار با میوپی ‎-4.00 D‎ و آستیگماتیسم منظم ‎-1.00 D‎ در محور ۱۸۰ درجه، کدام لنز تماسی نرم توریک مناسب‌تر است؟

  1. لنز با محور ۹۰ درجه و نشانگر پایدار
  2. لنز کروی ‎-4.00 D‎
  3. لنز کروی ‎-5.00 D‎
  4. لنز با محور ۱۸۰ درجه و طراحی پایدارکننده Correct answer.

Explanation

در لنز توریک، محور استوانه باید با محور آستیگماتیسم قرنیه هم‌راستا باشد؛ بنابراین محور ۱۸۰ درجه و طراحی پایدارکننده برای جلوگیری از چرخش لازم است. استفاده از لنز کروی، آستیگماتیسم را اصلاح نمی‌کند.

Question 10Optics, Refraction and Contact Lenses

در یک چشم با کراتوکونوس و لنز تماسی سخت، کدام یافته نشانه نامناسب بودن تطابق لنز است؟

  1. حلقه اشک اشکی یکنواخت در لبه لنز
  2. تماس مرکزی لنز با آپکس قرنیه Correct answer.
  3. عدم وجود رنگ‌آمیزی فلورسئین
  4. پایداری لنز در حین پلک زدن

Explanation

در قوزقرنیه، لنز سخت باید بر روی قله قرنیه بنشیند و از تماس مستقیم با آپکس جلوگیری کند. تماس مرکزی باعث تحریک، رنگ‌آمیزی و کاهش تحمل لنز می‌شود و نشانه تطابق نامناسب است.

Question 11Optics, Refraction and Contact Lenses

کدام اصل در مورد عدسی‌های فتوکرومیک صحیح است؟

  1. فعال‌سازی آن‌ها به نور ماورای بنفش وابسته است. Correct answer.
  2. تیرگی آن‌ها با افزایش دما بیشتر می‌شود.
  3. در داخل خودرو همیشه به حداکثر تیرگی می‌رسند.
  4. فعال‌سازی آن‌ها به نور مرئی وابسته است.

Explanation

مولکول‌های فتوکرومیک با جذب نور ماورای بنفش تغییر ساختار داده و تیره می‌شوند. شیشه خودرو بخش زیادی از ماورای بنفش را جذب می‌کند، بنابراین در خودرو تیرگی کمتر است.

Question 12Optics, Refraction and Contact Lenses

بیماری با پریسبیوپی و نیاز به دید نزدیک در فاصله ۳۳ سانتی‌متر، با افزودن ‎+3.00 D‎ رضایت ندارد. کدام گزینه بهترین رویکرد است؟

  1. افزایش افزودن به ‎+3.50 D‎ بدون توجه به فاصله کاری
  2. استفاده از عدسی پیشرفته با طراحی تدریجی و ارزیابی مجدد Correct answer.
  3. کاهش افزودن و افزایش فاصله کاری
  4. تجویز عدسی تک‌کانونی برای دور

Explanation

نارضایتی در دید نزدیک می‌تواند ناشی از عدم تطابق طراحی عدسی با نیازهای کاری باشد و ارزیابی مجدد با طراحی تدریجی یا افزودن مناسب‌تر کمک‌کننده است. افزایش کورکورانه افزودن بدون ارزیابی فاصله کاری ممکن است مشکل را حل نکند.

Question 13Optics, Refraction and Contact Lenses

کدام عامل در انتخاب لنز تماسی برای کودک با آفاکی پس از جراحی آب‌مروارید بیشترین اهمیت را دارد؟

  1. نفوذپذیری اکسیژن و پیگیری رشد چشم Correct answer.
  2. قطر لنز بزرگ‌تر از حد استاندارد
  3. قدرت استوانه‌ای ثابت
  4. رنگ لنز

Explanation

در کودکان آفاکیک، نیاز به اکسیژن‌رسانی مناسب و پیگیری مکرر قدرت انکساری به دلیل رشد چشم ضروری است. لنز باید با تغییرات رشد سازگار باشد و از عوارض هیپوکسی جلوگیری کند.

Question 14Optics, Refraction and Contact Lenses

در عدسی تدریجی، کدام ناحیه بیشترین اعوجاج محیطی را ایجاد می‌کند؟

  1. مرکز عدسی
  2. ناحیه نزدیک
  3. نواحی جانبی (پراکندگی محیطی) Correct answer.
  4. ناحیه دور

Explanation

در عدسی‌های تدریجی، تغییر تدریجی قدرت در مسیر عمودی باعث ایجاد نواحی پراکندگی در دو طرف راهروی اصلی می‌شود که اعوجاج محیطی ایجاد می‌کند. این نواحی معمولاً خارج از مسیر دید اصلی قرار دارند.

Question 15Optics, Refraction and Contact Lenses

برای بیمار با خشکی چشم متوسط که می‌خواهد از لنز تماسی نرم استفاده کند، کدام اقدام مناسب‌تر است؟

  1. استفاده از لنز سخت بدون ارزیابی خشکی
  2. افزایش زمان استفاده روزانه بدون ارزیابی
  3. استفاده از لنز با محتوای آب پایین و مواد سیلیکون‌هیدروژل Correct answer.
  4. استفاده از لنز با محتوای آب بالا و تعویض مکرر

Explanation

در خشکی چشم، لنزهای با محتوای آب پایین و نفوذپذیری اکسیژن بالا مانند سیلیکون‌هیدروژل کمتر آب اشک را جذب می‌کنند و تحمل بهتری ایجاد می‌کنند. ارزیابی و پیگیری خشکی نیز ضروری است.

Question 16Optics, Refraction and Contact Lenses

کدام یافته در آزمون دوچشمی نشان‌دهنده آنیزومتروپی قابل توجه است؟

  1. تساوی کامل انکسار دو چشم
  2. اختلاف انکساری بیش از ۱ دیوپتر بین دو چشم Correct answer.
  3. اختلاف تنها در محور استوانه
  4. اختلاف انکساری کمتر از ۰٫۲۵ دیوپتر

Explanation

آنیزومتروپی به اختلاف معنادار انکسار بین دو چشم گفته می‌شود و اختلاف بیش از ۱ دیوپتر معمولاً از نظر بالینی قابل توجه است. این وضعیت می‌تواند باعث آنیزیکونیا و اختلال دید دوچشمی شود.

Question 17Cornea and External Eye Disease

A 28-year-old contact lens wearer presents with a 6 mm corneal epithelial defect, a soft contact lens still in place, and a positive fluorescein staining. Which organism must be assumed and treated empirically until cultures return?

  1. Pseudomonas aeruginosa Correct answer.
  2. Herpes simplex virus type 1
  3. Acanthamoeba species
  4. Staphylococcus epidermidis

Explanation

In contact lens-associated microbial keratitis, Pseudomonas aeruginosa is the most frequent and most rapidly destructive pathogen, so empirical therapy must cover it with a fluoroquinolone or fortified aminoglycoside. Delay in anti-pseudomonal treatment risks corneal melting and perforation.

Question 18Cornea and External Eye Disease

A dendritic epithelial lesion with terminal bulbs stains with fluorescein and shows reduced corneal sensation. Which topical agent is the mainstay of therapy?

  1. Topical prednisolone acetate 1%
  2. Topical acyclovir ointment Correct answer.
  3. Topical moxifloxacin
  4. Topical trifluridine plus a topical steroid

Explanation

A dendritic ulcer with terminal bulbs and reduced sensation is classic for epithelial herpes simplex keratitis, treated with topical antiviral therapy such as acyclovir ointment or ganciclovir gel. Topical steroids alone are contraindicated in active epithelial disease because they promote viral replication.

Question 19Cornea and External Eye Disease

Which clinical finding most strongly supports a diagnosis of Acanthamoeba keratitis rather than bacterial keratitis in a soft contact lens wearer?

  1. Hypopyon with a dense central stromal infiltrate
  2. Epithelial defect with feathery margins and mucopurulent discharge
  3. Radial keratoneuritis with pain out of proportion to signs Correct answer.
  4. Circumcorneal injection with purulent discharge

Explanation

Acanthamoeba keratitis characteristically produces perineural infiltrates (radial keratoneuritis) and severe pain that seems disproportionate to the visible findings, often with a ring infiltrate later in the course. Purulent discharge and dense suppuration point instead toward bacterial infection.

Question 20Cornea and External Eye Disease

A patient with a 4 mm central corneal ulcer, hypopyon, and severe pain is started on fortified topical antibiotics. Which additional immediate step is most appropriate?

  1. Therapeutic soft contact lens placement
  2. Immediate penetrating keratoplasty
  3. Topical steroid at high frequency
  4. Corneal scraping for smears and cultures before or at initiation of therapy Correct answer.

Explanation

Corneal scrapings for Gram stain, cultures, and smears should be obtained at the time therapy is started so that the causative organism can be identified and treatment adjusted. Surgical intervention and steroids are reserved for specific situations and are not the immediate next step in a new ulcer.

Question 21Cornea and External Eye Disease

Which topical medication is the treatment of choice for a documented fungal corneal ulcer caused by Fusarium species?

  1. Amphotericin B 0.15% drops
  2. Voriconazole 1% drops
  3. Natamycin 5% suspension Correct answer.
  4. Fluconazole 0.2% drops

Explanation

Natamycin 5% is the only commercially available topical ophthalmic antifungal and is the first-line agent for filamentous fungal keratitis, including Fusarium. It has good activity against filamentous molds and is preferred over systemic-only or compounded alternatives as initial therapy.

Question 22Cornea and External Eye Disease

A 65-year-old with rheumatoid arthritis develops peripheral corneal thinning with an overhanging epithelial edge and severe pain. Which underlying mechanism best explains this presentation?

  1. Peripheral ulcerative keratitis driven by immune complex deposition and collagenolysis Correct answer.
  2. Age-related endothelial decompensation
  3. Chronic staphylococcal blepharoconjunctivitis
  4. Limbal stem cell deficiency from contact lens wear

Explanation

Peripheral ulcerative keratitis in rheumatoid arthritis results from immune complex deposition at the limbus, complement activation, and release of matrix metalloproteinases that degrade corneal stroma. It is a vision-threatening ocular emergency requiring systemic immunosuppression in addition to topical therapy.

Question 23Cornea and External Eye Disease

Which finding best distinguishes Mooren ulcer from peripheral ulcerative keratitis associated with systemic vasculitis?

  1. Elevated erythrocyte sedimentation rate
  2. Bilateral involvement at presentation
  3. Absence of an identifiable systemic disease and no scleritis Correct answer.
  4. Presence of anterior scleritis

Explanation

Mooren ulcer is a diagnosis of exclusion: it is a painful, progressive peripheral ulcerative keratitis without associated systemic disease and without scleritis. Systemic vasculitis-related peripheral ulcerative keratitis typically occurs with scleritis and systemic inflammatory markers.

Question 24Cornea and External Eye Disease

A patient with severe dry eye has a rose bengal staining pattern of the inferior conjunctiva and a decreased Schirmer test. Which mechanism underlies the ocular surface damage?

  1. Hyperosmolarity with reduced tear film stability and tear film deficiency Correct answer.
  2. Overproduction of aqueous tears by the lacrimal gland
  3. Increased corneal endothelial pump activity
  4. Excess mucin production by goblet cells

Explanation

Dry eye disease is driven by tear film hyperosmolarity and instability, which cause epithelial damage and the rose bengal staining of devitalized cells. A reduced Schirmer test reflects aqueous deficiency contributing to this cycle.

Question 25Cornea and External Eye Disease

Which topical agent used for ocular surface anesthesia can cause severe corneal epithelial toxicity and is not recommended for repeated use?

  1. Tetracaine 0.5%
  2. Lidocaine 2% gel
  3. Proparacaine 0.5% Correct answer.
  4. Oxybuprocaine 0.4%

Explanation

All topical anesthetics are toxic to the corneal epithelium with repeated use; proparacaine is a commonly abused agent that can cause epithelial sloughing, delayed healing, and even stromal melting. Topical anesthetics should be used only for procedures and never prescribed for home use.

Question 26Cornea and External Eye Disease

A patient using topical timolol develops punctate epithelial erosions and a dry eye sensation. Which mechanism most likely explains this adverse effect?

  1. Allergic conjunctivitis from the beta-blocker
  2. Increased aqueous tear secretion
  3. Preservative (benzalkonium chloride) toxicity and reduced tear production Correct answer.
  4. Direct beta-blocker-induced corneal edema

Explanation

Benzalkonium chloride in preserved glaucoma drops causes epithelial toxicity and reduced tear film stability, and beta-blockers can reduce tear production. Switching to a preservative-free formulation often resolves the symptoms.

Question 27Cornea and External Eye Disease

Which corneal dystrophy is characterized by bilateral, symmetric, breadcrumb-like opacities in the anterior stroma that stain with Masson trichrome and typically spare the peripheral cornea?

  1. Lattice corneal dystrophy
  2. Fuchs endothelial dystrophy
  3. Macular corneal dystrophy
  4. Granular corneal dystrophy Correct answer.

Explanation

Granular corneal dystrophy (TGFBI mutation) produces discrete breadcrumb or granular opacities in the anterior stroma with clear intervals between lesions and peripheral sparing. Macular dystrophy instead causes diffuse cloudy opacities extending to the limbus.

Question 28Cornea and External Eye Disease

A 45-year-old with recurrent corneal erosions and branching refractile lines in the stroma has a family history of corneal disease. Which gene mutation is most likely responsible?

  1. COL8A2
  2. CHST6
  3. TGFBI Correct answer.
  4. SLC4A11

Explanation

Lattice corneal dystrophy, like granular and Reis-Bücklers dystrophies, is caused by mutations in the TGFBI gene encoding keratoepithelin. The refractile branching lines and recurrent erosions are characteristic of lattice dystrophy type 1.

Question 29Cornea and External Eye Disease

Which finding on slit-lamp examination is most characteristic of Fuchs endothelial corneal dystrophy?

  1. Anterior stromal breadcrumb opacities
  2. Central guttae with corneal edema and reduced endothelial cell count Correct answer.
  3. Subepithelial arcus-like lipid deposition
  4. Peripheral corneal thinning with an overhanging edge

Explanation

Fuchs dystrophy is characterized by central posterior corneal guttae, progressive endothelial cell loss, and corneal edema that is worse on waking. The edema results from failure of the endothelial pump.

Question 30Cornea and External Eye Disease

A 30-year-old with keratoconus has progressive inferior corneal thinning and astigmatism. Which finding on corneal topography is most consistent with this diagnosis?

  1. Central flattening with regular astigmatism
  2. Inferior steepening with asymmetric bow-tie pattern Correct answer.
  3. Superior steepening with symmetric bow-tie pattern
  4. Diffuse irregular astigmatism with normal pachymetry

Explanation

Keratoconus classically shows inferior corneal steepening with an asymmetric bow-tie pattern on topography, along with inferior thinning on pachymetry. These findings help distinguish it from other ectatic or refractive conditions.

Question 31Cornea and External Eye Disease

Which treatment is most appropriate for a patient with progressive keratoconus and a corneal thickness of 480 microns at the thinnest point?

  1. Corneal collagen cross-linking Correct answer.
  2. Photorefractive keratectomy
  3. Penetrating keratoplasty
  4. Radial keratotomy

Explanation

Corneal collagen cross-linking is indicated for progressive keratoconus to halt progression, and a thinnest pachymetry of at least 400 microns is generally acceptable with appropriate protocols. Refractive surgery is contraindicated in keratoconus, and keratoplasty is reserved for advanced disease.

Question 32Cornea and External Eye Disease

Which condition is a contraindication to corneal collagen cross-linking?

  1. Pellucid marginal degeneration with progression
  2. Progressive keratoconus in a 20-year-old
  3. Corneal thickness less than 400 microns at the thinnest point without a protective protocol Correct answer.
  4. Post-LASIK ectasia

Explanation

A thinnest corneal thickness below 400 microns is a relative contraindication to standard cross-linking because of the risk of endothelial damage from ultraviolet exposure. Specialized protocols such as hypo-osmolar riboflavin or a contact lens barrier may allow treatment in selected cases.

Question 33Cornea and External Eye Disease

A patient with a history of herpes zoster ophthalmicus develops persistent epithelial defects and neurotrophic keratopathy. Which topical therapy promotes epithelial healing in this setting?

  1. Topical steroid at high frequency
  2. Autologous serum tears Correct answer.
  3. Topical anesthetic drops
  4. Topical antibiotic prophylaxis alone

Explanation

Neurotrophic keratopathy results from loss of corneal sensation, and autologous serum tears provide growth factors that support epithelial healing. Topical anesthetics are contraindicated, and steroids can impair healing.

Question 34Cornea and External Eye Disease

Which clinical sign is most consistent with a diagnosis of ocular cicatricial pemphigoid rather than Stevens-Johnson syndrome?

  1. Progressive conjunctival shrinkage with fornix foreshortening and subepithelial fibrosis Correct answer.
  2. Acute hemorrhagic crusting of the lips
  3. History of a new medication preceding onset
  4. Diffuse macular rash with epidermal detachment

Explanation

Ocular cicatricial pemphigoid is a chronic autoimmune disease causing progressive conjunctival scarring, fornix foreshortening, symblepharon, and subepithelial fibrosis. Stevens-Johnson syndrome is an acute drug- or infection-triggered reaction with acute systemic and mucocutaneous findings.

Question 35Cornea and External Eye Disease

Which topical medication is most appropriate for the acute management of adenoviral epidemic keratoconjunctivitis?

  1. Topical antiviral drops
  2. Topical steroid drops
  3. Supportive therapy with artificial tears and hygiene measures Correct answer.
  4. Topical antibiotic drops

Explanation

Adenoviral keratoconjunctivitis is self-limited and managed with supportive care, including artificial tears and strict hygiene to limit spread. Antibiotics, steroids, and antivirals do not alter the course of uncomplicated disease.

Question 36Cornea and External Eye Disease

A patient with a history of atopic dermatitis presents with bilateral itchy, ropy discharge and cobblestone papillae on the upper tarsal conjunctiva. Which diagnosis is most likely?

  1. Atopic keratoconjunctivitis Correct answer.
  2. Giant papillary conjunctivitis
  3. Vernal keratoconjunctivitis
  4. Seasonal allergic conjunctivitis

Explanation

Atopic keratoconjunctivitis occurs in patients with atopic dermatitis and features bilateral itching, ropy discharge, and papillary reaction, with the upper tarsal conjunctiva commonly involved. It can cause sight-threatening corneal complications such as shield ulcers.

Question 37Cornea and External Eye Disease

Which finding on corneal examination is most consistent with a shield ulcer in vernal keratoconjunctivitis?

  1. A dendritic epithelial lesion
  2. A ring-shaped stromal infiltrate
  3. Peripheral corneal thinning with an overhanging edge
  4. A central epithelial defect with a plaque-like deposit and thickened edges Correct answer.

Explanation

Vernal shield ulcers are typically central or superior epithelial defects with elevated, thickened edges and a fibrinous plaque that can delay healing. They result from chronic allergic inflammation and mechanical trauma from giant papillae.

Question 38Cornea and External Eye Disease

Which surgical approach is preferred for a patient with a central corneal scar and a normal endothelium?

  1. Descemet membrane endothelial keratoplasty
  2. Descemet stripping endothelial keratoplasty
  3. Deep anterior lamellar keratoplasty Correct answer.
  4. Penetrating keratoplasty

Explanation

Deep anterior lamellar keratoplasty replaces the anterior cornea while preserving the patient's own endothelium, reducing the risk of endothelial rejection and graft failure. It is preferred when the pathology is confined to the stroma and the endothelium is healthy.

Question 39Cornea and External Eye Disease

Which finding is most characteristic of a failing penetrating corneal graft due to endothelial rejection?

  1. Graft-host interface scarring without inflammation
  2. A Khodadoust line with graft edema and keratic precipitates Correct answer.
  3. Subepithelial infiltrates without edema
  4. A clear graft with stable refraction

Explanation

Endothelial rejection presents with a Khodadoust line, keratic precipitates, and graft edema as donor endothelial cells are attacked. Prompt intensive topical and systemic steroid therapy is required to reverse the process.

Question 40Cornea and External Eye Disease

A patient with severe dry eye and filamentary keratitis is evaluated. Which topical treatment is most appropriate to reduce filaments and surface inflammation?

  1. Topical antibiotic drops
  2. Preservative-free artificial tears with a short course of topical steroid Correct answer.
  3. Topical anesthetic drops
  4. Topical antiviral ointment

Explanation

Filamentary keratitis results from severe tear film instability and epithelial damage, so treatment targets the underlying dry eye with preservative-free lubrication and a short course of topical steroid to reduce inflammation. Topical anesthetics are contraindicated.

Question 41Lens and Cataract Surgery

A 68-year-old man reports gradual painless blurring of distance and near vision over two years. Slit-lamp examination shows central lens opacity with visible spokes and a clear periphery. Which type of cataract is most consistent with this finding?

  1. Cortical cataract Correct answer.
  2. Nuclear sclerotic cataract
  3. Anterior polar cataract
  4. Posterior subcapsular cataract

Explanation

Cortical cataracts begin as radial spoke-like opacities in the cortex and are classically described as cuneiform or wedge-shaped, often with a clear center until late stages. They typically cause glare and blurred vision as the spokes reach the visual axis. Nuclear sclerosis produces diffuse yellowing and hardening of the nucleus, while posterior subcapsular opacity sits just anterior to the posterior capsule.

Question 42Lens and Cataract Surgery

Which systemic medication is most strongly associated with the development of posterior subcapsular cataract?

  1. Long-term systemic corticosteroids Correct answer.
  2. Levothyroxine
  3. Amlodipine
  4. Metformin

Explanation

Prolonged systemic corticosteroid use is a well-established risk factor for posterior subcapsular cataract, and the risk rises with dose and duration. The opacity forms just anterior to the posterior capsule and can cause disproportionate glare and near-vision loss. Metformin, amlodipine, and levothyroxine are not classically linked to this cataract subtype.

Question 43Lens and Cataract Surgery

During phacoemulsification, which maneuver is performed to bring the nucleus into the anterior chamber after capsulorrhexis and hydrodissection?

  1. Nucleus rotation and prolapse into the anterior chamber Correct answer.
  2. Anterior vitrectomy
  3. Hydrodelineation
  4. Capsular polishing

Explanation

After hydrodissection frees the nucleus from the cortex and capsule, the surgeon rotates the nucleus and lifts it into the anterior chamber so that phacoemulsification can proceed safely away from the posterior capsule. This step reduces the risk of capsule rupture and endothelial trauma. Hydrodelineation separates the epinucleus from the endonucleus rather than prolapsing the nucleus.

Question 44Lens and Cataract Surgery

A 72-year-old woman has a dense white cataract and a history of high myopia. Which preoperative finding most increases the risk of posterior capsule rupture during phacoemulsification?

  1. Corneal arcus
  2. Shallow anterior chamber with a thick lens
  3. Zonular laxity with phacodonesis Correct answer.
  4. Mild nuclear sclerosis

Explanation

Zonular weakness with phacodonesis signals instability of the lens–capsule complex, which predisposes to capsule rupture and lens dislocation during surgery. It requires gentler technique, possible capsule tension ring use, and a lower threshold for converting to extracapsular extraction. High myopia itself is associated with zonular weakness, but the visible finding of phacodonesis is the direct risk marker.

Question 45Lens and Cataract Surgery

A patient with a brunescent nucleus and hard cataract undergoes phacoemulsification. Which strategy best reduces the risk of thermal corneal injury during phacoemulsification?

  1. Increasing ultrasound power and reducing aspiration
  2. Employing a dispersive ophthalmic viscosurgical device and intermittent phaco bursts Correct answer.
  3. Reducing irrigation flow to improve visibility
  4. Using a larger incision and lowering the bottle height

Explanation

Hard nuclei require more phaco energy, and dispersive viscoelastic plus intermittent burst phacoemulsification limits continuous energy delivery and protects the endothelium. Adequate irrigation and aspiration flow are essential to dissipate heat at the tip. Reducing irrigation or increasing power with low aspiration worsens heat buildup and wound burn risk.

Question 46Lens and Cataract Surgery

Which formula parameter most affects intraocular lens power calculation in eyes with axial length greater than 26 mm?

  1. Pupil diameter
  2. Axial length measurement Correct answer.
  3. Corneal astigmatism
  4. Anterior chamber depth estimation

Explanation

In highly myopic eyes, small errors in axial length measurement translate into large refractive errors because the eye is long and the effective lens position differs from emmetropic eyes. Accurate biometry, preferably optical, is therefore critical. Modern formulas such as Barrett and Hill-RBF handle long eyes better than older formulas, but axial length accuracy remains the dominant factor.

Question 47Lens and Cataract Surgery

A patient with a history of recurrent uveitis develops a cataract and is scheduled for surgery. Which preoperative measure most reduces the risk of postoperative inflammation and complications?

  1. Routine use of a silicone intraocular lens
  2. Aggressive control of intraocular inflammation for at least three months before surgery Correct answer.
  3. Discontinuation of all immunosuppressive therapy
  4. Immediate surgery during active inflammation

Explanation

In uveitic cataract, surgery should be performed when the eye has been quiet for at least three months, with perioperative corticosteroids and control of systemic disease. Operating during active inflammation markedly increases the risk of fibrin formation, synechiae, and cystoid macular edema. Silicone lenses are generally avoided in uveitis because of the higher risk of inflammation and deposits.

Question 48Lens and Cataract Surgery

A 65-year-old man with diabetes and no retinopathy undergoes uneventful phacoemulsification. Which finding on postoperative day one most suggests acute bacterial endophthalmitis rather than expected inflammation?

  1. Mild conjunctival injection
  2. Severe pain with hypopyon and marked vitritis Correct answer.
  3. Mild anterior chamber reaction with a quiet pupil
  4. Corneal edema at the incision site

Explanation

Acute bacterial endophthalmitis typically presents within days with severe pain, marked anterior chamber reaction, hypopyon, and vitritis, often with decreased vision. Mild postoperative inflammation and localized incision edema are common and expected. A hypopyon with vitritis after cataract surgery requires urgent vitreous sampling and intravitreal antibiotics.

Question 49Lens and Cataract Surgery

Which capsulorrhexis diameter best optimizes overlap of the anterior capsule over the intraocular lens optic in routine phacoemulsification?

  1. 7.5 mm
  2. 5.0 to 5.5 mm Correct answer.
  3. 9.0 mm
  4. 2.0 mm

Explanation

A continuous curvilinear capsulorrhexis of about 5.0 to 5.5 mm typically allows the anterior capsule edge to overlap the optic, stabilizing the lens and reducing the risk of posterior capsule opacification. A very small opening increases the risk of capsular phimosis, while a large opening may fail to overlap the optic. The size should be adjusted to pupil and optic diameter.

Question 50Lens and Cataract Surgery

A patient with pseudoexfoliation syndrome is undergoing cataract surgery. Which intraoperative adjunct most helps stabilize the capsular bag when zonular weakness is present?

  1. Intracameral acetylcholine
  2. Capsular tension ring Correct answer.
  3. Trypan blue dye
  4. Anterior chamber maintainer

Explanation

A capsular tension ring redistributes tension around the weakened zonules and stabilizes the capsular bag during phacoemulsification and lens implantation in pseudoexfoliation. Trypan blue aids visualization of the capsule in white cataracts, and acetylcholine constricts the pupil. Neither of these addresses zonular instability directly.