Maharashtra HSC Ophthalmic Technician (Vocational) flashcards

31 cards. Read the term and the definition here. The deck at the top of this page is optional.

Aqueous humour drainage pathway

Aqueous humour produced by the ciliary epithelium passes through the pupil, enters the anterior chamber angle, filters through the trabecular meshwork, and drains via Schlemm canal into episcleral veins.

Fovea centralis function

The fovea is a small depression in the macula containing densely packed cones and no rods, giving the highest visual acuity and colour discrimination under good illumination.

Superior oblique nerve supply

The superior oblique muscle is supplied by the trochlear nerve, cranial nerve four. Its action includes depression, intorsion and abduction of the eye.

Prism dioptre definition

One prism dioptre deviates a light ray by one centimetre at a distance of one metre. Prisms are used to measure and compensate ocular deviations.

Snell law

Snell law states that the ratio of the sine of the angle of incidence to the sine of the angle of refraction equals the ratio of refractive indices of the two media.

Thin lens combination formula

For two thin lenses in contact, total power equals the sum of individual powers. When separated by distance d, subtract the product term d times F1 times F2.

Spherical equivalent formula

The spherical equivalent equals the spherical power plus half of the cylindrical power. It is used for contact lens selection and for estimating overall refractive error.

Retinoscopy working distance correction

The working distance lens, such as plus one point five dioptres at sixty-six centimetres, is subtracted from the neutralising lens to obtain the patient's net refractive error.

Duochrome test principle

The red-green duochrome test exploits chromatic aberration. With the best sphere, red and green targets appear equally clear; over-minus makes red clearer, under-minus makes green clearer.

Keratometry purpose

Keratometry measures anterior corneal curvature and calculates corneal power, typically around forty-three to forty-four dioptres. It is essential for contact lens fitting and corneal assessment.

Goldmann applanation tonometry

Goldmann tonometry flattens a fixed corneal area using a calibrated biprism with fluorescein and cobalt blue light; the dial reading multiplied by ten gives intraocular pressure in millimetres of mercury.

Direct ophthalmoscopy image

A direct ophthalmoscope produces an upright, virtual image magnified about fifteen times, with a small field of view. It is useful for optic disc and macula assessment.

Lensmeter function

A lensmeter, or focimeter, verifies the spherical power, cylindrical power, axis and optical centre of spectacles. It is used for quality control and for checking patients' current glasses.

Angle-closure glaucoma features

Acute angle closure presents with severe eye pain, headache, halos around lights, nausea, reduced vision, a mid-dilated fixed pupil and a shallow anterior chamber. It is an emergency.

Diabetic retinopathy signs

Non-proliferative diabetic retinopathy shows microaneurysms, dot and blot haemorrhages and hard exudates. Proliferative disease adds neovascularisation with risk of vitreous haemorrhage and traction.

Trachoma causative organism

Trachoma is caused by Chlamydia trachomatis serovars A to C. Repeated infection causes conjunctival scarring, trichiasis, entropion and corneal opacity leading to blindness.

Wet macular degeneration

Wet age-related macular degeneration involves choroidal neovascular membranes causing sudden distortion and vision loss. Urgent referral is needed because treatment is time-sensitive.

Snellen acuity notation

Snellen acuity is recorded as the test distance over the distance at which a normal eye would read the same line, such as six over six. It is not a percentage of vision.

Pinhole test interpretation

A pinhole reduces blur circles from refractive error, so acuity improves when the cause is uncorrected ametropia. It does not improve acuity caused by media opacity or retinal disease.

Ishihara plate purpose

Ishihara plates screen for red-green colour vision deficiency using pseudoisochromatic patterns. They detect congenital defects but are not a full colour vision assessment.

Seidel test

The Seidel test applies fluorescein to a suspected corneal wound. A dark stream diluting the green fluorescence indicates aqueous leakage and possible perforation requiring urgent care.

Punctal occlusion after drops

Pressing on the nasolacrimal sac for one to two minutes after instilling drops reduces drainage into the nose and systemic absorption, lowering adverse effects of drugs like beta-blockers.

Drop instillation technique

Instil drops into the lower fornix with the patient looking up, without touching the bottle tip to the eye or lashes, to maintain sterility and patient comfort.

Vasovagal syncope management

If a patient faints during a procedure, lie them flat, elevate the legs, protect the airway, monitor breathing and pulse, and call for clinical assistance.

Tropicamide action

Tropicamide is a short-acting antimuscarinic that dilates the pupil and paralyses accommodation. It is used for fundus examination and refraction, with effects lasting a few hours.

Timolol contraindications

Timolol is a non-selective beta-blocker used in glaucoma. It is contraindicated in asthma, severe obstructive airway disease and heart block because of systemic absorption.

Topical anaesthetic caution

Topical anaesthetics such as proxymetacaine are for procedures only. Repeated or chronic use causes corneal epithelial toxicity and delayed healing and must be avoided.

Sterilisation versus disinfection

Sterilisation destroys all micro-organisms including bacterial spores, whereas disinfection reduces the number of pathogens but may not eliminate spores. Autoclaving is a sterilisation method.

Standard precautions principle

Standard precautions treat all blood and body fluids as potentially infectious regardless of diagnosis. They include hand hygiene, gloves, eye protection and safe sharps disposal.

Vitamin A deficiency effects

Vitamin A deficiency causes night blindness and xerophthalmia, including conjunctival xerosis, Bitot spots and corneal ulceration. Supplementation and dietary improvement are preventive measures.

Contemporaneous record keeping

Clinical records must be written at the time of care or as soon as possible, dated, signed and factual. Late entries are clearly marked and original entries are never altered.