Key points 14 Flashcards
Hard exudates are found in which layer of the retina:
caused by underperfusion leading to damage to the endothelium of deep capillaries. This causes leakage of plasma into the outer plexiform layer.
Which landmark study evaluated the effect of tight blood pressure and blood sugar control on diabetic retinopathy in Type 1 diabetics?
DCCT
Which landmark study evaluated the effect of tight blood pressure and blood sugar control on diabetic retinopathy in Type 2 diabetics?
UKPDS
When is generally considered the optimal time for surgical repair of orbital floor fractures:
1 to 2 weeks post-injury provides a chance for orbital swelling and contusion diplopia to resolve and yet is early enough to avoid problems with scarring of a significant floor fracture.
The Early Vitrectomy Study (EVS) found that for patients with post-operative endophthalmitis an early vitrectomy leads to a better visual outcome compared to standard intravitreal antibiotics if the presenting vision is:
PL or worse early vitrectomy led to a three-fold increase in the number of these patients ultimately achieving 6/12 or better.
What are the features of Incontinentia pigmenti
X-linked dominant
skin lesions which evolve from blistering in newborn, to macular hyperpigmentation in childhood to linear hypopigmentation in adulthood
alopecia
hypodontia
neurological problems e.g. cerebral atrophy
ocular features include: vascular abnormalities in the peripheral retina including capillary non-perfusion, AV shunts, fibrovascular proliferation, and neovascularisation, which may progress to retinal detachment. It can also be associated with cataract and with combined harmatoma of the RPE and retina.
Structures visible on gonioscopy from anterior to posterior are:
Schwalbe’s line, non-pigmented trabecular meshwork, pigmented trabecular meshwork, scleral spur, ciliary body
The major immunoglobulin constituent in human tears is:
The major immunoglobulin class found in human tears is IgA. IgD has not been detected in any study of human tears.
Place the following retinal injuries in order of their frequency following blunt ocular injury (MOST frequent first):
- Tears around lattice
- Giant retinal tears
- Inferotemporal dialysis
- Superonasal dialysis
- Flap tears
inferotemporal dialysis
superonasal dialysis (contra-coup injury)
giant tear
flap tear
tear around lattice
For a patient to be reassured that systemic disease is unlikely, ocular myasthenia should remain localized for what length of time?
82% of patients who later developed generalized weakness did so in the first 2 years after diagnosis of ocular myasthenia.[2] Hence, patients who keep having strictly ocular symptoms for 2 or more years are unlikely to revert to the generalized aspect of the disease.
A patient is suffering from the following symptoms since commencing a recent medication: dry eyes, inflamed conjunctiva, corneal ulceration, mouth ulceration and target skin lesions.
What is the most likely drug?
The clinical features described are consistent with Stevens-Johnson syndrome, which can be caused by many drugs, including the sulpha antibiotics
What is the most common malignant tumour of the lacrimal sac
SCC
A brainstem lesion that involves the medial longitudinal fasciculus as well as the ipsilateral abducens nucleus will most likely cause:
A lesion of the abducens nucleus will often involve the nearby PPRF and result in an ipsilateral gaze paresis. A lesion that also disrupts the ipsilateral MLF will result in the combination of an ipsilateral gaze palsy and internuclear ophthalmoplegia. This combination has been termed the one-and-a-half syndrome. The only horizontal eye movement that remains is contralateral abduction.
Which muscles are affected most commonly in thyroid eye disease?
The order of involvement of ocular muscles in thyroid eye disease is (most common first):
inferior rectus
medial rectus
superior rectus
levator
lateral rectus
Oblique muscles are rarely involved in TED.
What are the causes of chronic follicular conjunctivitis?
trachoma (Chlamydia serotypes A to C)
adult inclusion conjunctivitis (Chlamydia serotypes D to K)
molloscum contagiosum
drug-induced (e.g. brimonidine)
bacterial: e.g. Parinaud’s oculoglandular syndrome/Cat scratch/Lyme
Axenfeld’s follicular conjunctivitis
Merril-Thygeson
rosacea blepharitis
The two most commonly encountered chemical compositions of band keratopathy are:
calcium
urate
Which feature is most helpful in differentiating between actinic keratosis and seborrheic keratosis:
Epithelial atypia is not a feature of seborrheic keratosis, but is present in actinic keratosis. Both lesions are characterised by hyperpigmentation and inflammation.
Which is most likely to cause orbital hyperostosis?
Orbital hyperostosis is thickening of the bony walls of the orbit. It may occur in benign osseous tumours, most commonly meningioma. It may also occur in malignant bone tumours such as osteosarcoma and in metastatic lesions as in prostate carcinoma.
According to Alexander’s law, in which position should upbeat nystagmus be most prominent?
Alexander’s law refers to the increased frequency and amplitude of nystagmus movements accompanying gaze in the direction of the fast-beating component. Downbeat nystagmus most frequently violates the law.
A 40-year-old patient with a chronic history of sinusitis presents with a 10-day history of worsening right-sided painful proptosis and chemosis. There is severe limitation of right eye movements in all directions and a right RAPD. Slit lamp examination reveals sclerokeratitis.
The findings are most in keeping with:
sclerokeratitis, orbital disease and co-existing sinus disease raise suspicion of Wegener’s.
A patient is diagnosed with normal tension glaucoma and prescribed latanoprost drops at night to both eyes. On routine review 3-month later, it is noted that he has reduced visual acuity in his right eye and visual field progression compared to the last visit bilaterally.
Which investigation is most important?
The differential of NTG must always include lesions of the visual pathway. A sudden progression of visual fields and loss of visual acuity are not consistent with glaucoma, and an alternative diagnosis should be sought urgently by arranging an MRI of the brain and orbits.
Acute idiopathic blind spot enlargement is considered a possible spectrum of which condition:
Acute idiopathic blind spot enlargement shares many features with MEWDS. These two conditions, along with acute macular neuroretinopathy, may represent spectra of the same disorder.
Presumed ocular histoplasmosis syndrome is most common in which geographic location:
Presumed ocular histoplasmosis syndrome is almost exclusively found in the United States, especially in the Midwest. This, despite the fact that the histoplasma capsulatum fungus is found throughout the world in river valleys.
The correct spot size for argon laser trabeculoplasty (ALT) is:
50-micron beam with variable power to produce blanching or a tiny bubble at the anterior pigmented edge of the trabecular meshwork. Typically 180 degrees is treated at one sitting. Outflow facility typically improves following successful ALT.
What is ICE syndrome
proliferation and migration of abnormal corneal endothelial cells, which grow over all structures in the anterior chamber. Growth of abnormal cells over the corneal endothelium leads to corneal decompensation which frequently requires corneal grafting. Meanwhile growth over the trabecular meshwork and iris leads to progressive closed-angle glaucoma, which ensues in over 50% of ICE eyes.
Which surgical correction is good for a patient with large lower lid defect following BCC excision (80%)?
ideally requires a Hughes flap but this is a 2-stage procedure with the second stage occurring 6-10 weeks after the first, and the eye is covered during this time. Similarly, the Cutler-Beard flap occludes the visual axis.
Which surgical correction is good for a patient with large lower lid defect following BCC excision (80%) and cannot afford to be monocular?
A posterior lamellar graft with skin mobilization is the preferred choice. A graft should ideally be covered by a local vascularised flap to ensure good supply, and this is achieved by a Fricke flap. The graft can be sourced from the opposite upper lid.
When is a Tenzel flap performed?
only suitable if the horizontal defect is less than 70%.
Which chromosome or gene defect is associated with retinoblastoma:
13
Which landmark study evaluated the effect of aspirin on diabetic retinopathy?
The ETDRS study evaluated the outcome of early macular laser treatment in clinically significant macular oedema, PRP in early proliferative diabetic retinopathy and the effect of aspirin in diabetic retinopathy.
The distribution of intra-ocular pressure (IOP) in the population is:
Gaussian with a skew to the right. The mean IOP is 16mmHg with a range of 11-21mmHg within 2 standard deviations of the mean.
In which condition is a drainage implant MOST likely to be used as a first-line surgical option?
Drainage implants are considered in the following circumstances:
previous failed trabeculectomy with adjuvant antimetabolite
neovascular glaucoma
traumatic angle recession glaucoma
eyes with severe conjunctival scarring
congenital glaucomas where conventional procedures (e.g goniotomy or trabeculotomy) have failed
A mother brings in her 6-month-old son for evaluation of excessive tearing from both of his eyes. On examination, the child is noted to be photophobic and have corneal clouding.
What is the best course of action to take?
presentation is suspicious for bilateral infantile glaucoma. If possible, the diagnosis may be made in the office through IOP measurement, cycloplegic refraction (induced myopia), and optic nerve examination. In most cases, however, the patient needs to be taken to the operating room to confirm the diagnosis and to initiate surgical correction while under the same anaesthesia.
Which of the following metals can produce a pyogenic response if retained in tissue:
Retained tissue copper produces a pyogenic immune response for reasons that are not understood.
A steroid molecule attached to which compound will be MOST likely to penetrate the cornea to reach the anterior chamber:
acetate
A patient on cyclophosphamide is most likely to develop which side effect:
most common side effect is bone-marrow suppression, particularly granulopoiesis and lymphopoiesis, which is almost universal.
The ratio of rods to cones in the human retina is:
120 million rods and 6 million cones in the retina.
What is the Pulfrich phenomenon
reflects delayed conduction in the demyelinated nerve and occurs where oscillating objects viewed binocularly and moving in one plane (e.g. pendulum) appear to have three-dimensional movement.
