Oral boards peds Flashcards
Cloudy and enlarged cornea DDx
Congenital glaucoma
Congenital hereditary endothelial dystrophy (CHED)
Congenital hereditary Stromal Dystrophy (CHSD)
STUMPED (sclerocornea, trauma, ulcers, metabolic, peters, PPMD, dermoid)
encephalofacial angiomatosis (Sturge-Weber syndrome?_
Cloudy and enlarged cornea History/Exam
History: photophobia, epiphora, blepharospasm
FH of inherited conditions: congenital glaucoma or CHED?
History of trauma (i.e forceps) and maternal infection during pregnancy
Exam: VA, RAPD
Consider exam under anesthesia:
Anterior segment exam: K edema and K diameter (> 12 mm suggests congenital glaucoma), horizontal breaks in DM (Haab striae), K thickness (pachymetry)
Gonioscopy may reveal abnormal angle anatomy assoc/w/congenital glaucoma
Evaluate eye pressure, perform DFE evaluating ON for cupping and R/O diffuse choroidal hemangiomas (encephalofacial angiomatosis)
Cycloplegic retinoscopy to determine myopic shift 2/2 progressive elongation (i.e. congenital glaucoma)
Examine adnexa for port-wine stains (encephalofacial angiomatosis) and for abrasions/scars assoc/w/trauma to help narrow DDx
Congenital glaucoma A/P
Plan: surgical intervention (goniotomy or glaucoma procedure - trab or tube - likely tube) to lower IOP and preserve ON function.
Initiate Rx with oral and topical IOP lowering agents initially to gauge response and buy time until surgery possible.
AVOID brimonidine 2/2 apnea risk
Congenital glaucoma education
Medical/surgical Rx will be required throughout life.
In addition to pressure lowering concerns, we will need to monitor for amblyopia. Guarded prognosis but useful VA can be maintained with monitoring and treatment.
White spot on eye DDx
JIA
RD - chronic
intraocular silicone oil
trauma with subsequent phthisical eye
metabolic d/o (hyper PTH, hyperCa, Vitamin D)
inflammatory conditions (sarcoidosis, gout) and malignancy
Synergist muscle (ex: RSR)
ipsilateral muscle that acts in the same direction
ex: RIO = elevation or RSO = intorsion
Antagonist muscle (ex: RSR)
ipsilateral muscle that acts in the OPPOSITE direction
(Ex: RIR = depression vs. elevation
OR
RIO = extorsion vs. intorsion)
Yoke muscle
contralateral muscles that are the prime movers for a given position of gaze
ex: YOKE to RMR is the LLR (left gaze)
ex: YOKE to RSR is LIO (up and to the right)
Primary vs. secondary deviation
The primary deviation is misalignment, with the normal eye fixating. If the paretic eye fixates, the ensuing secondary deviation is typically larger than the primary deviation.
Herring’s law explains why secondary deviation is greater than primary deviation in paretic and restrictive strabismus.
Single cover test (cover-uncover test)
The single cover test is generally performed first. This is done by using an opaque or translucent (fogged) occlude to occlude one eye. The occluder is simply held in front of the eye for a few seconds and then removed. If a tropia is present in the non-occluded eye, the examiner will observe the contralateral eye move to pick up fixation when the fixing eye is occluded. If not, the eye will remain stationary. The presence of ANY movement on a single cover test indicates a tropia.
In the case of a phoria, or latent deviation, the examiner observes the eye underneath the occluder. In the case of a phoria, the uncovered eye does not move however the eye that is under the cover will deviate when occluded and return to a straight position when the occluder is removed. The cover-uncover test can differentiate whether the misalignment is a phoria or a tropia.
The monocular cover-uncover test is the most important test for detecting the presence of manifest strabismus and for differentiating a heterophoria from a heterotropia. As 1 eye is covered, the examiner watches carefully for any movement in the opposite, noncovered eye; such movement indicates the presence of a heterotropia. With movement of the noncovered eye assumed to be absent, movement of the covered eye in one direction just after the cover is applied and a movement in the opposite direction (a fusional movement) as the cover is removed indicate a heterophoria that becomes manifest only when binocularity is interrupted. If the patient has a heterophoria, the eyes will be straight before and after the cover-uncover test; the deviation that appears during the test is a result of interruption of binocular vision. A patient with a heterotropia, however, starts out with a deviated eye and ends up (after the test) with either the same or the opposite eye deviated (if the opposite eye is the deviated one, the condition is termed alternating heterotropia). Some patients may have straight eyes and start out with a heterophoria prior to the cover-uncover test; however, after prolonged testing—and therefore prolonged interruption of binocular vision—dissociation into a manifest heterotropia can occur.
Alternate cover test
For this test, the examiner occludes one eye and then the other, switching the occluder back and forth to occlude the eyes without allowing the patient to fuse in between occlusion.
The alternate cover test is the most dissociative cover test and measures a total deviation, including the tropic plus the phoric/latent component.
When performing the alternate cover test it is important to hold the occlude over each eye for at least a few seconds, in order to allow the non-occluded eye enough time to pick up fixation. In general, the faster the eyes are able to recover when the occluder is switched, the better the control of the deviation.
The alternate cover test (prism and cover test) measures the total deviation, regardless of whether it is latent or manifest (Fig 6-2). This test does not specify how much of each type of deviation is present (ie, it does not separate the heterophoria from the heterotropia). This test should be done at both distance and near fixation. Once dissociation is achieved, the amount of deviation is measured using prisms to eliminate the eye movement as the cover is alternately switched from eye to eye. It may be necessary to use both horizontally and vertically placed prisms. The amount of prism power required is the measure of deviation. Two horizontal or 2 vertical prisms should not be superimposed on each other because this can induce significant measurement errors. Their values cannot be directly added. A more accurate method for measuring large deviations is to place prisms in front of each eye, although it should be noted that these are not perfectly additive either. However, it is acceptable to superimpose a horizontal prism on a vertical prism before the same eye if necessary.
Alternate prism cover test
The alternate prism cover test is similar to the alternate cover test, with the addition of a prism held over one eye to quantify the misalignment. Prisms should be held in the “frontal plane” so that the rear face of the prism is parallel to the plane of the patient’s face. The examiner then performs the alternate cover test while holding prism over the deviated eye until the misalignment is neutralized. The misalignment is quantified with the size of the prism (measured in Prism Diopters) which is required to neutralize the deviation.
Whereas the alternate cover test measures the total deviation (heterophoria and heterotropia), the simultaneous prism and cover test is helpful in determining the actual heterotropia when both eyes are uncovered (heterotropia alone). The test is performed by covering the fixating eye at the same time the prism is placed in front of the deviating eye. The test is repeated using increasing prism powers until the deviated eye no longer shifts. This test has special application in monofixation syndrome, which may include a small-angle heterotropia. Patients with this condition may reduce the amount of deviation measured in the alternate cover test by exerting at least partial control over a coexisting heterophoria through peripheral fusion when both eyes are open. In this instance, the simultaneous prism and cover test measures the amount of heterotropia in a deviation that has a superimposed heterophoria. This test may be useful in assessing the deviation under real-life conditions with both eyes viewing.
