MRCSI (Ophth) Written key terms

A reduced pupil constriction when light is shone into one eye compared with the other, caused by disease of the retina or optic nerve on that side. Detected with the swinging flashlight test.

The measurable asymmetry in pupillary response between the two eyes during the swinging flashlight test, graded in log units. It localises disease to the conducting pathway of the affected eye, not the iris.

The sharpness of central vision, measured as the smallest optotype a patient can resolve at a standard distance and recorded as a fraction or logMAR value.

The bending of light as it passes through the cornea and lens to focus on the retina; also the clinical process of determining the lens power needed to correct a patient's focus.

A refractive state in which parallel light rays focus in front of the retina, making distant objects blurred while near vision is relatively preserved. Corrected with concave (minus) lenses.

A refractive error in which the cornea or lens has unequal curvature in different meridians, so light is focused at more than one point and vision is blurred at all distances.

Reduced vision in one or both eyes caused by abnormal visual experience during early development, with no structural abnormality explaining the loss. Treatable if detected early.

Misalignment of the eyes in which the visual axes are not parallel, producing a manifest or latent deviation. May be concomitant or paralytic and can cause amblyopia or diplopia.

A clinical test in which one eye is covered while the other fixates, then the cover is moved, to reveal manifest and latent ocular deviation and to distinguish tropia from phoria.

Perception of two images of a single object. Binocular diplopia resolves when either eye is covered and usually reflects misalignment; monocular diplopia persists and suggests optical or retinal causes.

Opacity of the crystalline lens that reduces the amount of light reaching the retina and degrades image quality. The commonest cause of reversible blindness worldwide.

Cataract surgery technique in which the lens nucleus is fragmented with ultrasonic energy and aspirated through a small incision, usually with implantation of an intraocular lens.

An artificial lens implanted inside the eye, most often in the capsular bag after cataract extraction, to replace the optical power of the removed crystalline lens.

A group of optic neuropathies characterised by progressive retinal ganglion cell loss and characteristic optic disc cupping, with raised intraocular pressure being the major modifiable risk factor.

The fluid pressure within the eye, determined mainly by the balance between aqueous humour production by the ciliary body and outflow through the trabecular meshwork. Normal range roughly 10 to 21 mmHg.

Occlusion of the drainage angle by the peripheral iris, causing acute or chronic rise in intraocular pressure. Acute presentation includes pain, haloes, a fixed mid-dilated pupil and corneal haze.

A filtering operation for glaucoma in which a partial-thickness scleral flap and opening into the anterior chamber allow aqueous to drain into the subconjunctival space, creating a bleb.

Damage to the optic nerve from ischaemic, inflammatory, compressive, toxic or glaucomatous causes, producing reduced acuity, colour desaturation, field loss and an afferent pupillary defect.

The total area a patient can see while the eye is steadily fixating, mapped by perimetry. Defect patterns help localise lesions along the visual pathway.

Loss of half of the visual field in one or both eyes. Bitemporal loss suggests a chiasmal lesion; homonymous loss suggests a retrochiasmal lesion.

Bilateral optic disc swelling caused by raised intracranial pressure, typically with preserved acuity but enlarged blind spots and headache. A sign, not a diagnosis.

Separation of the neurosensory retina from the retinal pigment epithelium, causing a shadow or curtain across vision. Rhegmatogenous detachment follows a retinal tear.

Perception of flashes of light, typically caused by mechanical stimulation of the retina such as vitreous traction at a retinal tear or detachment.

Surgical removal of vitreous gel from the eye, performed for conditions such as retinal detachment, vitreous haemorrhage or macular disease, often with gas or oil tamponade.

Microvascular damage to the retina from chronic hyperglycaemia, producing microaneurysms, haemorrhage, exudates, macular oedema and, in proliferative disease, new vessels that bleed or detach the retina.

Fluid accumulation within the macula causing central blurring, commonly from diabetic retinopathy, venous occlusion or post-operative inflammation. Assessed with optical coherence tomography.

Laser treatment applied to peripheral retina to reduce ischaemic drive and induce regression of new vessels in proliferative diabetic retinopathy or other ischaemic retinopathies.

A non-invasive imaging technique using low-coherence light to produce cross-sectional images of the retina and optic nerve head, used to detect and monitor macular oedema and ganglion cell loss.

Progressive thinning and conical protrusion of the cornea causing irregular astigmatism and reduced vision. Managed with rigid contact lenses and corneal cross-linking; severe cases need transplantation.

Replacement of part or all of the cornea with donor tissue, either full thickness (penetrating) or partial (lamellar), for opacity, ectasia or endothelial failure.

Infection within the eye, usually bacterial after surgery or trauma, presenting with pain, falling vision, hypopyon and vitritis. A sight-threatening emergency requiring intravitreal antibiotics.

Treatment of amblyopia by patching or otherwise obscuring the better eye to force use of the amblyopic eye during the sensitive developmental period.

A benign tumour of the pituitary gland that can compress the optic chiasm, classically producing bitemporal hemianopia and sometimes endocrine hypersecretion or failure.

Dysfunction of one of the twelve cranial nerves; in ophthalmology most relevant are III, IV and VI, causing ptosis, pupil changes, vertical or horizontal diplopia and impaired eye movement.

The process of obtaining a patient's voluntary, informed agreement to an investigation or operation after explaining its nature, benefits, risks, alternatives and the consequences of refusal.

A patient's ability to understand, retain and weigh information and communicate a decision about their care. Assessed functionally; lacking it triggers best-interests decision-making.

A structured three-phase checklist (sign in, time out, sign out) used in theatre to confirm patient identity, site, procedure, allergies and equipment, reducing avoidable harm.

Infection arising at or near an operation site within 30 days of surgery (or one year if an implant is placed), classified as superficial, deep or organ-space. A key quality indicator.

Life-threatening organ dysfunction caused by a dysregulated host response to infection, identified clinically by a rise in the sepsis-related organ failure score. Requires urgent antibiotics and source control.

Rapid intravenous administration of crystalloid or colloid to restore circulating volume in shock or dehydration, titrated against clinical response and monitored for overload.

A state of inadequate tissue perfusion producing cellular hypoxia, classified as hypovolaemic, cardiogenic, distributive or obstructive. Presents with hypotension, tachycardia and poor perfusion.

Mechanical or functional blockage of intestinal transit causing colicky pain, vomiting, distension and absolute constipation. Managed with resuscitation and decompression; strangulation requires surgery.

Surgical opening of the abdominal cavity, either elective or emergency, to access intra-abdominal organs for resection, repair, drainage or control of bleeding and contamination.

A surgical connection between two tubular structures, such as bowel ends, designed to restore continuity. Success depends on adequate blood supply, tension-free technique and healthy tissue.

Acute inflammation of the vermiform appendix, typically causing migratory right iliac fossa pain, anorexia, fever and localised peritonism. Treated by appendicectomy.

Minimally invasive surgery performed through small ports using a camera and instruments, offering reduced pain and faster recovery compared with open surgery but with specific risks.

Free gas within the peritoneal cavity, usually from a perforated hollow viscus and seen as free gas under the diaphragm on erect imaging. Also created deliberately for laparoscopy.

Inflammation of the peritoneum, commonly from bacterial contamination after perforation or ischaemia, causing rigid abdomen, guarding and systemic upset. Often needs urgent laparotomy.

Agreement to treatment given after the patient has received and understood information on diagnosis, proposed procedure, material risks, alternatives and likely outcomes.