A girl has pain and blurring of vision while reading

(A) (Asthenopia) (341, 346 Khurana 5th)Asthenopia (aesthenopia) from the Greek word "asthen-opia : aoGsv-Gma" or eye strain is an ophthalmological condition that manifests itself through nonspecific symptoms such as fatigue, pain in or around the eyes, blurred vision, headache and occasionaldouble vision. Symptoms often occur after reading, computer work, or other close activities that involve tedious visual tasks.When concentrating on a visually intense task, such as continuously focusing on a book or computer monitor, the ciliary muscletightens. This can cause the eyes to get irritated and uncomfortable. Giving the eyes a chance to focus on a distant object at least once an hour usually alleviates the problem.Sometimes, asthenopia can be due to specific visual problems, for example, uncorrected refraction errors or binocular vision problems such as accommodative insufficiency orheterophoria. It is often caused by the viewing of monitors such as those of computers or phones.ESOPHORIAEXOPHORIA* Common in younger group*** Increased accommodation* Excessive use of convergence may cause esophoria(as occurs in bilateral congenital myopes )* Dissociation factor such as prolonged constant use of one eye may result in exophoria (as occurs in individuals using uniocular microscope and watch makers using uniocular magnifying glass)* Elderly* Decreased accommodation* Decreased use of convergence is often associated with exophoria (as seen in presbyopes)Symptoms1. Muscular fatigue -(i) Headache(ii) Difficulty inchanging the focus(iii) Headache and eyeache(iv) Photophobia2. Symptoms of failure to maintain binocular single vision**(i) Blurring or crowding of words while reading(ii) Intermittent diplopia* Intermittent squint (without diplopia)3. Symptoms of defective postural sensation cause problems in judging distances and positions especially of the moving objects. This difficulty may be experienced by cricketers, tennis players and pilots during landing* Concomitant convergent squint - Esotropia* Concomitant divergent squint - Exotropia* Vertical squint - Hypertropia* Uncrossed diplopia is seen in convergent squint -(Esotropia)* Crossed diplopia is seen divergent squint -(Exotropia)CORTICAL BLINDNESS- Bilateral infarction in the distal posterior cerebral arteries* Direct and concensual reflexes are present in both the eyes**