Consider the following eye disorders 1. Cataract 2. Colour blindness 3. Night blindness Which of the above disorders is/are essentially genetic in nature ?

Colour blindness is essentially a genetic disorder, typically inherited as an X-linked recessive trait, which affects the eye's ability to detect specific colours [t3]. While cataract and night blindness can have genetic forms, they are not 'essentially' genetic as they are primarily associated with non-genetic factors. Cataracts are most commonly a result of the natural aging process where lens proteins crystallize and harden [c1, t7], though congenital forms exist [t4, t10]. Night blindness (nyctalopia) is most frequently caused by Vitamin A deficiency, which affects rhodopsin production in rod cells [t2, t7, t9]. Although conditions like Retinitis Pigmentosa or X-linked congenital stationary night blindness are genetic [t1, t6], the disorder itself is widely recognized as a symptom of nutritional deficiency or aging [t8]. Therefore, only colour blindness is fundamentally defined by its genetic nature in standard medical classification.

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 10: The Human Eye and the Colourful World > 10.1.1 Power of Accommodation > p. 162
2. [2] https://medlineplus.gov/genetics/condition/x-linked-congenital-stationary-night-blindness/
3. [3] https://en.wikipedia.org/wiki/Color_blindness
4. [4] https://pmc.ncbi.nlm.nih.gov/articles/PMC5465711/