A 14-year-old boy is brought to the clinic by his mother due to changes in vision. For the last few weeks, the patient has been squinting when trying to read the interactive whiteboard in class and has had to sit closer to the front of the room. He has also developed headaches. The patient has no chronic medical conditions and takes no medications. Temperature is 37.2 C (99 F), blood pressure is 116/76 mm Hg, and pulse is 70/min. Examination of the eyes shows equal and reactive pupils. Extraocular muscles are intact, and visual field testing reveals no defects. Visual acuity shows 20/70 in both eyes. His ability to read close text is normal. Which of the following is the most likely cause of this patient's symptoms?

Question

A 14-year-old boy is brought to the clinic by his mother due to changes in vision.  For the last few weeks, the patient has been squinting when trying to read the interactive whiteboard in class and has had to sit closer to the front of the room.  He has also developed headaches.  The patient has no chronic medical conditions and takes no medications.  Temperature is 37.2 C (99 F), blood pressure is 116/76 mm Hg, and pulse is 70/min.  Examination of the eyes shows equal and reactive pupils.  Extraocular muscles are intact, and visual field testing reveals no defects.  Visual acuity shows 20/70 in both eyes.  His ability to read close text is normal.  Which of the following is the most likely cause of this patient's symptoms?

Quizplus · Accepted Answer

11ec160b_3b15_fa58_9249_475d36b3a2ce_MD0001_00 This patient with decreased visual acuity and an otherwise normal ophthalmic examination likely has simple myopia (nearsightedness), a refractive error caused by an increased anterior-posterior diameter of the eye. The risk is greatest for those with a positive family history or those of East Asian descent. During the adolescent growth spurt, the axial length of the globe also grows rapidly, making the incidence of new-onset myopia highest in this age group. As the anterior-posterior diameter increases, the focal point of a refracted image lies anterior to the retina. For images to be seen clearly, they must be projected directly onto the retina; therefore, the image displacement in myopia causes blurred vision of long-distance objects and decreased visual acuity on examination. Vision of nearby objects is unaffected and appears clear in myopic patients. The remainder of the examination, including extraocular movements, peripheral field testing, and funduscopic examination, is normal. Management is with prescription glasses with a diverging (concave) lens, which refocuses the refracted image onto the retina. The degree of myopia usually stabilizes by early adulthood. (Choice A) Glaucoma, most commonly due to chronically elevated intraocular pressure, is characterized by optic neuropathy, as evidenced by optic cupping seen on funduscopic examination. Visual acuity may be affected but is a late manifestation after progressive loss of peripheral vision, which is normal in this patient. (Choice B) Untreated strabismus (misalignment of the eyes) in early childhood can cause unilateral visual cortex suppression to avoid diplopia and eventually lead to amblyopia (decreased visual acuity). This patient's recent symptom onset and normal extraocular movements make this diagnosis unlikely. (Choice D) Presbyopia is a nonrefractive error that increases with age due to the loss of accommodating power of the lens from decreased elasticity. Blurry vision of nearby objects typically develops in patients age >40. (Choice E) Hyperopia (farsightedness) is a refractive error characterized by a reduced anterior-posterior diameter of the eye, causing the focal point of the refracted image to be positioned posterior to the retina. In contrast to myopia, hyperopia causes blurred vision of nearby objects and is corrected by a converging (convex) lens. Educational objective: Myopia (nearsightedness) is a refractive error in which the focal point of an image falls anterior to the retina due to an increased anterior-posterior diameter of the eyes. Patients have difficulty seeing objects at a distance and have normal near vision. __________ References: Childhood myopia: epidemiology, risk factors, and prevention. (http://www.ncbi.nlm.nih.gov/pubmed/25958656) Prevention of progression in myopia: a systematic review. (http://www.ncbi.nlm.nih.gov/pubmed/30274355) The science behind myopia (http://www.ncbi.nlm.nih.gov/pubmed/29266913)

A 14-Year-Old Boy Is Brought to the Clinic by His