Preventable Blindness — MCQs
Arcuate field defect akin to glaucoma is seen in?
A multivariate analysis was conducted to examine the relationship between risk of developing blindness and age. The results are shown in the table below. Which of the following is true?
What does a visual acuity test primarily assess?
All of the following conditions are immediate priorities in the WHO's "Vision -2020: The Right to sight" except:
Under NPCB, screening of school children is first done by -
Which of the following procedures is not typically covered by the National Programme for Control of Blindness (NPCB) for reimbursement of surgery done by a non-governmental organization (NGO) eye hospital?
What is the definition of blindness according to WHO?
Vision 2020 "The right to sight" includes all except-
The golden period of eye donation is
Regarding Chlamydia infection of the eyes, true statements include the following except:
Preventable Blindness Indian Medical PG Practice Questions and MCQs
Question 1: Arcuate field defect akin to glaucoma is seen in?
- A. Optic nerve lesion (Correct Answer)
- B. Pituitary adenoma
- C. Posterior cerebral artery infarct
- D. None of the options
Explanation: ***Optic nerve lesion*** - An **arcuate field defect** is a specific pattern of visual field loss that follows the course of nerve fibers in the retina and is characteristic of **optic nerve damage**, similar to what is seen in glaucoma. - This type of defect is due to damage to the **bundle of retinal nerve fibers** that arch above or below the macula, often causing a scotoma (blind spot) that respects the horizontal meridian. - Common causes include **anterior ischemic optic neuropathy (AION)**, **optic neuritis**, and other optic nerve pathologies that affect the nerve fiber layer. *Pituitary adenoma* - A pituitary adenoma typically causes a **bitemporal hemianopsia** due to compression of the optic chiasm. - This visual field defect involves the lateral halves of both visual fields, which is different from an arcuate defect. *Posterior cerebral artery infarct* - An infarct in the posterior cerebral artery typically leads to a **homonymous hemianopsia** (loss of half of the visual field on the same side in both eyes) or a quadrantanopsia. - This type of defect results from damage to the **visual cortex** or optic radiations, not the optic nerve itself in a glaucoma-like pattern. *None of the options* - This is incorrect because **optic nerve lesion** is a valid and correct answer. - Optic nerve pathologies are well-established causes of arcuate field defects similar to those seen in glaucoma.
Question 2: A multivariate analysis was conducted to examine the relationship between risk of developing blindness and age. The results are shown in the table below. Which of the following is true?
- A. 60-69 y age group shows statistically significant association with blindness
- B. <50 y age group serves as the reference category
- C. >80 y age group has the strongest association with blindness risk (Correct Answer)
- D. 50-59 y age group has the highest odds ratio for blindness risk
Explanation: ***>80 y age group has the strongest association with blindness risk*** - The odds ratio for the **>80 years** age group is **2.1**, which is the highest among all age groups listed in the table, indicating the strongest association with blindness risk. - A higher odds ratio means a greater likelihood of the outcome (blindness) compared to the reference category. - All age groups shown have **p-values <0.001**, confirming statistical significance. *60-69 y age group shows statistically significant association with blindness* - While the 60-69 y age group has an odds ratio of **1.5** with **p<0.001**, indicating statistical significance, it does not have the strongest association compared to the **>80 y** age group (OR 2.1). - Statistical significance confirms the association is real, but effect size (OR) determines strength of association. *<50 y age group serves as the reference category* - The table shows an **Odds Ratio (OR) of 1.1** for the **<50 y** age group, indicating it is also being compared to a reference (which would have OR = 1.0). - The reference category is not explicitly shown in the table but would typically be an even younger age group or overall population baseline. *50-59 y age group has the highest odds ratio for blindness risk* - The odds ratio for the **50-59 y** age group is **1.2**, which is lower than the **>80 y** age group (OR 2.1), the **70-79 y** age group (OR 1.6), and the **60-69 y** age group (OR 1.5). - This statement is incorrect as the **>80 y** age group clearly has the highest odds ratio for blindness risk.
Question 3: What does a visual acuity test primarily assess?
- A. Ability to perceive light
- B. Ability to differentiate colors
- C. Ability to recognize shapes and details (Correct Answer)
- D. Ability to detect contrast
Explanation: ***Ability to recognize shapes and details*** - A visual acuity test, typically using a **Snellen chart**, measures the sharpness of vision, specifically the ability to discern letters or symbols at a given distance. - It assesses the eye's capacity to resolve fine **spatial detail**, which is crucial for tasks like reading and recognizing faces. - This is the fundamental definition of visual acuity and what these tests are specifically designed to measure. *Ability to perceive light* - This refers to **light perception (LP)**, the most basic form of vision, indicating whether a person can detect the presence or absence of light. - While essential for vision, it is a much simpler function than what visual acuity tests measure and is assessed separately. *Ability to differentiate colors* - This is assessed by **color vision tests**, such as the Ishihara plates, which evaluate the function of cone photoreceptors. - It specifically checks for **color blindness** (e.g., red-green or blue-yellow deficiencies) and is distinct from the sharpness of vision. *Ability to detect contrast* - This is measured by **contrast sensitivity tests**, which evaluate the ability to distinguish objects from their background at various contrast levels. - While related to overall visual quality, it is a different aspect of vision than the ability to recognize fine details at high contrast.
Question 4: All of the following conditions are immediate priorities in the WHO's "Vision -2020: The Right to sight" except:
- A. Cataract
- B. Epidemic conjunctivitis (Correct Answer)
- C. Onchocerciasis
- D. Trachoma
Explanation: ***Epidemic conjunctivitis*** - While **epidemic conjunctivitis** can cause significant discomfort and temporary vision impairment, it is generally **self-limiting** and rarely leads to permanent blindness. - It was not identified as one of the top five global causes of avoidable blindness targeted by the Vision 2020 initiative. *Cataract* - **Cataract** is the **leading cause of blindness** globally, accounting for approximately half of all cases. - It is a highly treatable condition through surgery, making it a critical priority for Vision 2020. *Onchocerciasis* - Also known as **river blindness**, onchocerciasis is a parasitic disease that causes severe visual impairment and blindness. - It is a significant public health problem in several regions, particularly in Africa, and was a key focus of Vision 2020 due to its widespread impact and the availability of preventive chemotherapy. *Trachoma* - **Trachoma** is the **leading infectious cause of blindness** worldwide, caused by *Chlamydia trachomatis*. - Given its preventable and treatable nature, and its prevalence in many impoverished areas, it was designated as one of the priority diseases under Vision 2020.
Question 5: Under NPCB, screening of school children is first done by -
- A. Ophthalmologic assistant
- B. Medical officer
- C. Village health guide
- D. School teachers (Correct Answer)
Explanation: ***School teachers*** - Under the **National Programme for Control of Blindness (NPCB)**, screening of school children follows a **three-tier approach**. - **School teachers** are trained to conduct the **first level/initial screening** using simple vision tests like **Snellen charts**. - They identify children with potential vision problems and refer them for further detailed assessment. - This approach maximizes coverage as teachers have regular contact with children and can screen large numbers efficiently. - The NPCB specifically includes **teacher training modules** for basic vision screening as part of the School Eye Screening Programme. *Ophthalmologic assistant* - Ophthalmic assistants/paramedical workers conduct the **second level screening** - the detailed assessment of children referred by teachers. - They perform comprehensive vision testing and identify specific refractive errors and eye conditions. - They are not the first point of contact in school screening due to resource limitations and the scale of screening required. *Medical officer* - Medical officers and ophthalmologists are involved in the **third tier** - providing diagnosis, treatment, and management of identified cases. - They handle complex cases, prescribe spectacles, and provide surgical interventions when needed. - They also supervise the overall program but do not conduct initial mass screening. *Village health guide* - Village health guides work primarily in community settings for general health promotion and basic healthcare. - While they contribute to community health awareness, they are not specifically involved in the structured school eye screening program under NPCB.
Question 6: Which of the following procedures is not typically covered by the National Programme for Control of Blindness (NPCB) for reimbursement of surgery done by a non-governmental organization (NGO) eye hospital?
- A. Cataract surgery
- B. Pan retinal photocoagulation for diabetic retinopathy
- C. Syringing and probing of the nasolacrimal duct (Correct Answer)
- D. Trabeculectomy surgery
Explanation: ***Syringing and probing of the nasolacrimal duct*** - While important for lacrimal drainage issues, procedures like **syringing and probing** are generally considered minor and less vision-restoring compared to the major surgeries targeted by the **NPCB**. - The **NPCB** focuses on interventions for leading causes of blindness, primarily **cataract** and other significant vision-threatening conditions, which this procedure typically isn't. *Cataract surgery* - **Cataract surgery** is a cornerstone of the **NPCB's** efforts, as cataracts are the leading cause of reversible blindness. - Reimbursement for **cataract surgery** is a primary objective to improve access and reduce the burden of blindness. *Pan retinal photocoagulation for diabetic retinopathy* - **Diabetic retinopathy** is a major cause of preventable blindness, and **pan retinal photocoagulation (PRP)** is a key intervention to preserve vision. - The **NPCB** includes procedures for **diabetic retinopathy** management due to its significant public health impact. *Trabeculectomy surgery* - **Trabeculectomy** is a surgical procedure for **glaucoma**, which is another significant cause of irreversible blindness. - The **NPCB** includes interventions for **glaucoma** given its severe vision-threatening nature and the need for surgical management in many cases.
Question 7: What is the definition of blindness according to WHO?
- A. Visual acuity of less than 10/60 in the better eye
- B. Visual acuity of less than 20/60 in the better eye
- C. Visual acuity of less than 6/60 in the better eye
- D. Visual acuity of less than 3/60 in the better eye (Correct Answer)
Explanation: ***Visual acuity of less than 3/60 in the better eye*** - According to the **World Health Organization (WHO)**, blindness is defined as a **presenting visual acuity** of less than 3/60 (or equivalent field loss) in the **better eye**. - This definition is crucial for **epidemiological studies**, public health planning, and determining eligibility for support services. *Visual acuity of less than 6/60 in the better eye* - A visual acuity of less than 6/60 in the better eye typically defines **severe visual impairment** according to WHO classifications, not complete blindness. - It represents a significant visual deficit but is not as profound as the 3/60 threshold for blindness. *Visual acuity of less than 10/60 in the better eye* - A visual acuity of less than 10/60 does not correspond to a standard WHO classification for either blindness or severe visual impairment. - This level of vision would generally fall within the range of **moderate visual impairment**, indicating a less severe condition than blindness. *Visual acuity of less than 20/60 in the better eye* - A visual acuity of less than 20/60 (or 6/18 in metric) in the better eye is often used as a threshold for **mild visual impairment** or **driving restrictions** in some regions. - This is a much milder degree of visual loss compared to the definition of blindness.
Question 8: 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 9: The golden period of eye donation is
- A. 24 hours
- B. 12 hours
- C. 18 hours
- D. 6 hours (Correct Answer)
Explanation: ***6 hours*** - The **golden period** for eye donation, specifically for the removal of the **cornea**, is ideally within **6 hours** of death. - This timeframe is critical to ensure the **viability and quality** of the corneal tissue for successful transplantation, as cellular degradation begins rapidly after cessation of circulation. *24 hours* - While some tissues can be recovered up to 24 hours post-mortem, the **cornea's viability** for transplantation significantly decreases after the initial 6-hour window. - Beyond 6 hours, the risk of **cellular damage** and reduced graft success rate increases considerably. *12 hours* - A 12-hour window is generally considered too long for optimal **corneal tissue viability**. - While tissue might still be recoverable, the **quality and success rate** of the transplant are significantly lower compared to donation within 6 hours. *18 hours* - An 18-hour period is far beyond the recommended timeframe for **corneal donation**. - At this point, the **cellular integrity** of the cornea is highly compromised, making it unsuitable for transplantation.
Question 10: Regarding Chlamydia infection of the eyes, true statements include the following except:
- A. Penicillin is the treatment (Correct Answer)
- B. Inclusion conjunctivitis is an acute ocular infection caused by sexually transmitted C. trachomatis strains (usually serovars D through K)
- C. Can be cultured
- D. Acute inclusion conjunctivitis typically presents with mucopurulent discharge
Explanation: ***Penicillin is the treatment*** - **Penicillin** is ineffective against *Chlamydia trachomatis* because *Chlamydia* lacks a **peptidoglycan cell wall**, which is the target of penicillin. - The standard treatment for chlamydial infections, including ocular infections, involves **azithromycin** or **doxycycline**. *Inclusion conjunctivitis is an acute ocular infection caused by sexually transmitted C. trachomatis strains (usually serovars D through K)* - **Inclusion conjunctivitis** is indeed caused by sexually transmitted serovars of *Chlamydia trachomatis* (typically **D through K**). - It usually occurs in sexually active adults and can affect neonates through maternal transmission. *Can be cultured* - *Chlamydia* are **obligate intracellular bacteria**, meaning they can only replicate inside host cells. - While they can be grown in cell cultures, this is a specialized technique and not a typical method for routine diagnosis due to its complexity and time-consuming nature. *Acute inclusion conjunctivitis typically presents with mucopurulent discharge* - **Acute inclusion conjunctivitis** is characterized by a **mucopurulent discharge**, along with **follicular conjunctivitis** and sometimes **preauricular lymphadenopathy**. - This discharge results from the inflammatory response to the chlamydial infection in the conjunctiva.
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