Epidemiology of Ocular Diseases — MCQs
Which of the following ocular findings is not associated with diabetes?
Which is the commonest cause of ocular morbidity in the community -
The eye condition for which the World bank assistance was provided to the National Programme for Control of Blindness:
A 2-year-old boy weighing 12 kg is diagnosed with vitamin A deficiency. What is the recommended oral dose of vitamin A for him?
What is the cause of glaucoma in retinoblastoma?
According to the WHO, what is the minimum distance at which a person is considered blind if they cannot count fingers in daylight?
The term enucleation means:
All are associated with Wernicke's encephalopathy, except:
Vision 2020 "The right to sight" includes all except-
Epithelial xerosis of conjunctiva is caused by?
Epidemiology of Ocular Diseases Indian Medical PG Practice Questions and MCQs
Question 1: Which of the following ocular findings is not associated with diabetes?
- A. Retinopathy
- B. Early senile cataract
- C. Neovascular glaucoma
- D. Blepharophimosis (Correct Answer)
Explanation: ***Blepharophimosis*** - This is a **congenital disorder** characterized by small palpebral fissures, ptosis, and epicanthus inversus, which is **not associated with diabetes**. - It is a **developmental anomaly** of the eyelids, with no known link to metabolic conditions like diabetes. *Retinopathy* - **Diabetic retinopathy** is a common and serious complication of diabetes, caused by damage to the blood vessels in the retina. - It can lead to vision loss if not managed, and is directly linked to **poor glycemic control**. *Early senile cataract* - Diabetes is a significant risk factor for the **earlier development and progression of cataracts**, including senile cataracts. - High blood sugar levels can cause changes in the lens, leading to **opacification** and impaired vision. *Neovascular glaucoma* - This severe form of **secondary glaucoma** is often a complication of advanced **diabetic retinopathy**. - Ischemia in the retina triggers the growth of **new blood vessels** on the iris and in the angle of the eye, obstructing aqueous outflow and raising intraocular pressure.
Question 2: Which is the commonest cause of ocular morbidity in the community -
- A. Vitamin A deficiency
- B. Ocular injury
- C. Refractive error (Correct Answer)
- D. Cataract
Explanation: ***Refractive error*** - **Uncorrected refractive errors**, such as **myopia**, **hyperopia**, and **astigmatism**, are the most common cause of avoidable visual impairment globally. - While not leading to complete blindness, they significantly reduce quality of life and productivity if not corrected with **spectacles** or **contact lenses**. *Vitamin A deficiency* - This deficiency is a major cause of **preventable childhood blindness** in developing countries. - It primarily leads to **xerophthalmia**, including **night blindness**, **Bitot's spots**, and ultimately **corneal scarring**. *Ocular injury* - **Trauma** to the eye can cause severe and permanent vision loss, especially in certain occupational settings or age groups. - However, the overall prevalence of significant ocular morbidity from injury in the general community is **lower** than that from uncorrected refractive errors. *Cataract* - **Cataracts** are the leading cause of **blindness worldwide**, particularly in older individuals. - While a major cause of visual impairment, it is most often treated with **surgery**, making uncorrected refractive errors a more prevalent cause of *morbidity* in the broader community that often goes undetected or unaddressed.
Question 3: The eye condition for which the World bank assistance was provided to the National Programme for Control of Blindness:
- A. Vitamin A deficiency
- B. Trachoma
- C. Cataract (Correct Answer)
- D. Onchocerciasis
Explanation: ***Cataract*** - The **National Programme for Control of Blindness (NPCB)**, with World Bank assistance, has focused heavily on **cataract surgeries** due to cataract being the leading cause of preventable blindness in India. - The program's aim was to provide accessible and affordable surgical interventions to clear the clouded lens, thereby restoring vision. *Vitamin A deficiency* - While vitamin A deficiency can lead to severe eye conditions like **xerophthalmia** and blindness, it's primarily addressed through nutritional programs and supplementary interventions, not the main focus of World Bank-assisted surgical initiatives within the NPCB. - Its prevention is mainly based on dietary changes and distribution of **vitamin A supplements**, especially in children. *Trachoma* - Trachoma is a bacterial eye infection that can cause blindness, particularly prevalent in regions with poor hygiene. - Although it's part of global blindness prevention efforts, the World Bank's assistance to the NPCB primarily targeted conditions requiring surgical intervention on a large scale, with **trachoma control** often involving antibiotic treatment and hygiene improvement rather than extensive surgical campaigns. *Onchocerciasis* - Onchocerciasis, or **river blindness**, is a parasitic disease primarily prevalent in sub-Saharan Africa. - It is not a major cause of blindness in India, thus not a primary focus of the **National Programme for Control of Blindness** or its World Bank-supported initiatives.
Question 4: A 2-year-old boy weighing 12 kg is diagnosed with vitamin A deficiency. What is the recommended oral dose of vitamin A for him?
- A. 200,000 I.U. (Correct Answer)
- B. 50,000 I.U.
- C. 100,000 I.U.
- D. 150,000 I.U.
Explanation: ***200,000 I.U.*** - According to **WHO guidelines**, for children aged **12 months and older** with vitamin A deficiency, the recommended oral dose is **200,000 I.U.** - This dose is given immediately upon diagnosis, repeated the next day, and a third dose is given 2-4 weeks later. - Since this child is **2 years old**, he falls into the ≥12 months category requiring 200,000 I.U. *100,000 I.U.* - A dose of **100,000 I.U.** is recommended for infants aged **6-11 months** with vitamin A deficiency. - This child is 2 years old, making 100,000 I.U. an insufficient dose for his age group. *50,000 I.U.* - A dose of **50,000 I.U.** is recommended for infants **younger than 6 months** diagnosed with vitamin A deficiency. - This dose is too low for a 2-year-old child. *150,000 I.U.* - **150,000 I.U.** is not a standard WHO-recommended dose for vitamin A deficiency treatment in any pediatric age group. - This is an incorrect dosing option.
Question 5: What is the cause of glaucoma in retinoblastoma?
- A. Neovascularisation (Correct Answer)
- B. Mass effect of the tumour
- C. Blockage of trabecular network
- D. Lysis of the lens
Explanation: ***Neovascularisation*** - Retinoblastoma leads to **neovascularization of the iris (NVI)** and **angle structures** due to tumor necrosis, ischemia, and release of **angiogenic factors (VEGF)**. - The **neovascular membrane** grows over and obstructs the **trabecular meshwork** and anterior chamber angle, causing **secondary neovascular glaucoma**. - This is the **most characteristic and common mechanism** of glaucoma in advanced retinoblastoma. - Neovascular glaucoma in retinoblastoma is typically **refractory to medical treatment** and indicates poor prognosis. *Blockage of trabecular network* - While tumor cells can directly seed into the anterior chamber and block the trabecular meshwork, this mechanism is **less common** than neovascularization. - This option is also **less specific** as it doesn't identify the underlying pathophysiological process (neovascularization) that is characteristic of retinoblastoma-associated glaucoma. - Direct trabecular blockage by tumor cells typically occurs in advanced disease and often coexists with neovascularization. *Mass effect of the tumour* - The tumor mass itself rarely causes glaucoma through direct mechanical compression of outflow pathways. - Retinoblastoma causes glaucoma primarily through **secondary mechanisms** such as inflammation, neovascularization, or cellular seeding, not simple bulk effect. - Massive tumors may cause angle closure, but this is uncommon compared to neovascular mechanisms. *Lysis of the lens* - **Phacolytic glaucoma** from lens protein leakage is rare in retinoblastoma. - While lens damage can occur with advanced tumors, it is **not a typical or characteristic cause** of glaucoma in retinoblastoma. - The primary mechanisms involve the **tumor-angle-trabecular meshwork axis**, not lens pathology.
Question 6: According to the WHO, what is the minimum distance at which a person is considered blind if they cannot count fingers in daylight?
- A. 1 metre
- B. 2 metres
- C. 3 metres (Correct Answer)
- D. 4 metres
Explanation: ***3 metres*** - The **WHO definition of blindness** includes the inability to count fingers at 3 meters (or 10 feet) in daylight. - This serves as a practical measure for severe **visual impairment** when standard acuity charts are unavailable. *1 metre* - While a significant visual impairment, the inability to count fingers at 1 meter is typically categorized as **severe visual impairment**, not outright blindness, by the WHO. - Severe visual impairment has a slightly less stringent threshold than the definition of blindness. *2 metres* - The inability to count fingers at 2 meters also falls under the category of **severe visual impairment**, according to WHO criteria. - It indicates significant vision loss but is not the specific distance used to define blindness when counting fingers. *4 metres* - A person unable to count fingers at 4 meters would certainly meet the criteria for **blindness**, as this is a greater distance than the 3-meter threshold. - However, the 3-meter mark is the **minimum specified distance** for this particular criterion of blindness by the WHO.
Question 7: The term enucleation means:
- A. Removal of eyeball contents
- B. Removal of the eyeball along with surrounding orbital tissue
- C. Removal of the eyeball along with extraocular muscles and part of skull
- D. Removal of eyeball along with a portion of optic nerve (Correct Answer)
Explanation: ***Removal of eyeball along with a portion of optic nerve*** - **Enucleation** specifically refers to the surgical removal of the entire eyeball, typically including a portion of the **optic nerve**. - The extraocular muscles are detached from the globe but remain in the orbit, along with orbital fat and other structures. - This procedure is commonly performed for conditions such as severe trauma, intraocular tumors, or a blind, painful eye. *Removal of eyeball contents* - This describes **evisceration**, a procedure where the contents of the eyeball are removed, leaving the scleral shell and extraocular muscles intact. - Evisceration is often chosen to maintain orbital volume and allow for better prosthetic motility. *Removal of the eyeball along with surrounding orbital tissue* - This would represent a more extensive procedure than enucleation alone. - In enucleation, the globe is removed but the extraocular muscles, orbital fat, and other orbital structures are preserved to maintain orbital volume and support prosthetic fitting. - Removal of orbital tissue beyond the globe itself would describe **orbital exenteration**. *Removal of the eyeball along with extraocular muscles and part of skull* - This extensive procedure is known as **orbital exenteration**, which involves removal of the entire orbital contents, including the eyeball, extraocular muscles, fat, and sometimes bone. - **Exenteration** is reserved for aggressive malignancies that have extended beyond the globe into the orbit.
Question 8: All are associated with Wernicke's encephalopathy, except:
- A. Cog wheel rigidity (Correct Answer)
- B. Alteration in mental function
- C. VIth nerve palsy
- D. Ataxia
Explanation: ***Cog wheel rigidity*** - **Cogwheel rigidity** is a characteristic symptom of **Parkinson's disease**, resulting from intermittent resistance to passive limb movement [1]. - It is not a feature of **Wernicke's encephalopathy**, which primarily affects different neurological pathways. *Alteration in mental function* - **Alteration in mental function**, ranging from confusion to coma, is a core feature of **Wernicke's encephalopathy** due to thiamine deficiency impacting brain metabolism [2],[3]. - This symptom is part of the classic triad, indicating diffuse cerebral dysfunction. *VIth nerve palsy* - **VIth nerve palsy** (abducens nerve palsy) often manifests as **ophthalmoplegia**, a key component of the Wernicke's triad [2]. - This cranial nerve dysfunction leads to impaired eye movements, particularly horizontal gaze abnormalities. *Ataxia* - **Ataxia**, characterized by a wide-based gait and poor coordination, is a common finding in **Wernicke's encephalopathy** [2]. - It results from damage to the cerebellum and vestibular system due to **thiamine deficiency** [3].
Question 9: Vision 2020 "The right to sight" includes all except-
- A. Measles induced blindness (Correct Answer)
- B. Onchocerciasis
- C. Trachoma
- D. Cataract
Explanation: ***Measles induced blindness*** - Vision 2020 primarily targets conditions that are either preventable or treatable with *cost-effective interventions* and contribute significantly to *avoidable blindness*. - While measles can cause blindness, the specific program focuses on a defined list of priority diseases for intervention, and measles-related blindness is generally addressed through broader public health initiatives (vaccination) rather than direct "right to sight" surgical or direct medical interventions for established blindness. *Onchocerciasis* - **Onchocerciasis** (river blindness) is a major focus of Vision 2020 due to its profound impact on sight, particularly in endemic areas. - It is a **preventable** and **treatable** cause of blindness through mass drug administration. *Trachoma* - **Trachoma** is recognized as one of the leading infectious causes of blindness globally and is explicitly targeted by Vision 2020 through the **SAFE strategy** (Surgery, Antibiotics, Facial cleanliness, Environmental improvement). - It is a highly **preventable** and **treatable** condition, fitting the program's objectives. *Cataract* - **Cataract** is the leading cause of blindness worldwide and is highly **treatable** through a relatively simple and cost-effective surgical procedure. - Providing cataract surgery is a cornerstone of the Vision 2020 initiative to restore sight.
Question 10: Epithelial xerosis of conjunctiva is caused by?
- A. Xerophthalmia (Correct Answer)
- B. Infectious conjunctivitis caused by Chlamydia trachomatis
- C. Autoimmune blistering conjunctivitis
- D. Bacterial conjunctivitis due to Corynebacterium diphtheriae
Explanation: ***Xerophthalmia*** - **Xerophthalmia** is a medical condition characterized by **dryness of the eye**, often due to **vitamin A deficiency**. - **Epithelial xerosis of the conjunctiva** is one of the early and hallmark signs of xerophthalmia, representing the drying and thickening of the conjunctival epithelium due to goblet cell loss and squamous metaplasia. *Infectious conjunctivitis caused by Chlamydia trachomatis* - This typically causes **trachoma**, characterized by chronic inflammation, scarring, and eventual blindness. - While it can lead to dryness and scarring in later stages due to **symblepharon** or **entropion**, it does not primarily manifest as epithelial xerosis. *Autoimmune blistering conjunctivitis* - This condition involves **immune-mediated inflammation** leading to subepithelial blistering, scarring, and shrinkage of the conjunctiva. - It results in significant **ocular surface damage** and vision loss but is distinct from the primary epithelial changes seen in xerosis due to vitamin A deficiency. *Bacterial conjunctivitis due to Corynebacterium diphtheriae* - **Diphtheritic conjunctivitis** is a severe form of bacterial conjunctivitis that causes a distinctive **"pseudomembrane"** on the conjunctiva. - It leads to acute inflammation and potentially systemic illness, not primarily epithelial xerosis.
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