Candidate 39
Date: February, 2005
Centre: Dundee
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1. Calculate the AC/A ratio in a patient who has 25PD of esotropia for near without glasses and with +3D lens esotropia is 5PD at 1/3 meter.

Ans  : 6.6PD of AC/1D of accommodation.

2. Calculate the power of a new lens if the BVD of a 10D lens is moved from 10mm to 12 mm. 
(Type of the lens was not mentioned. Examiner asked us to assume it as convex lens).

Ans: 9.8D

3. FFA and colour fundus photographs.

  • What is the investigation?
  • What is the principle?
  • Describe the findings?

  • Ans : FFA of the left eye- The arteriolar, early venous and venous phase showing clearly demarcated large area of initial Hypofluorescence in the macula with  late venous phase showing slowly progressive hyperfluorescence of constant size.--------suggestive of “staining” of the lesion—Disciform / fibrous scar.
    (Many wrote it as PED. However PED will have early hyperfluorescence with progressive hyperfluorescence in the late phases ie, pooling of the dye in a closed space soon after dye entering the choroidal circulation)

4. Ultrasound B Scan:

  • What is this investigation?
  • Describe the features.
  • What structure is involved?

  • Ans: B scan shows uniformly echodense funnel shaped band like structure attached to optic nerve head. 
    The structure involved; Retina: Probably long-standing funnel shaped RD with PVR  changes.Vitreous: Probably Partial thickened PVD with vitreous haemorrhage.
    [B scan was a photocopy and was not suggestive of either classical RD or PVD. The AL of the eye ball in that ‘view’ of scan also appeared short, however I preferred not to comment on these aspects.]

    5. Maddox Rod—red:

  • What is this instrument?
  • Draw a ray diagram depicting its principle.

  • 6. Hess chart:

  • What is this investigation?
  • What is the principle?
  • What does it show?
  • What is the diagnosis?
  • Ans: Hess chart was showing the muscle sequale of R 3rd Cranial nerve palsy.Principle- I wrote Hering’s and Sherrington’s law.
    7. CT scan:
    • What is this investigation/
    • Describe the findings?
    • How does the patient present?
    Ans(I am not sure): CT scan of the skull and orbit (axial view) showing echodense bony hyperostosis at the medial wing of the sphenoid bone involving the orbital apex (R).---probably due to sphenoidal meningioma involving the medial aspect.
    C/F—Disc edema, optic atrophy, Field defects, proptosis
    [ CT scan was also showing enlarged medial rectus muscle on both sides which was the answer by many. The scan appeared to be challenging one]
    8. Visual Field Test:
    • What is this investigation?
    • Is it reliable? Why do you say so?
    • Describe the findings.
    • Where is the lesion located?
    Ans: Binocular Esterman Visual fields showing R homonymous inferior quadrantinopia extending upto fixation. The lesion is located in Left  parietal lobe.


    Station 1: 
    Focimetry— I wrote wrong axis eventhough power was correct. Asked why green light is used and the principle of focimetry. [The focimeter looked very old model and the graticule for the axis was situated at the eye piece and I was not familiar about this model. I explained this to the examiner] Javal-Schiotz Keratometer-- asked to measure RE. Again I wrote correct power in dioptres but the axis was reverse!!. Asked regarding the principle.

    Station 2:

    Slit-lamp—asked to examine left eye of a patient—Relatively clear cornea with trabeculectomy bleb superiorly. AC was uniformly shallow with convex iris configuration and mid dilated fixed pupil with post synechiae and total cataract.---asked about the diagnosis—later examiner gave me a pentorch and asked to demonstrate visual fields in the left eye of the same patient—Before checking VF by confrontation, I tested perception of light---patient had projection of light only inferotemporally—then asked to correlate.

    Visual Fields-- Asked to do confrontation test in LE of a wheel chair bound gentleman.
    Patient had left homonymous hemianopia—asked about the visual pathway and the possible site of pathology---asked why red pin used for the central field.

    Station 3:

    Pupil—patient had right RAPD—Near reflex appeared normal, however it was difficult to appreciate the reaction---asked causes/site of lesion for RAPD.

    Ocular motility—asked to examine the ocular motility of a middle aged patient and to answer while testing—mild right exotropia in primary position—cover test showed elevation & mild abduction of the ‘covered’ eye with no movement of the fixing eye, there was no changes in the palpebral fissure—answered as bilateral DVD---then ocular movements showed limitation of abduction, laevoelevation and laevodepression---Examiner persistently asked to correlate the findings but I couldn’t {right exo + elevation & abduction of the covered eye(bilateral) + limitation of abduction in the left eye}—asked in whom the DVD is common??

    [Some answered it as bilateral Duane’s, Bilateral 4th nerve palsy. Some said there was also limitation of adduction in the left eye. I am not sure of the exact diagnosis, but there was a definite DVD]

    Station 4:

    Direct Ophthalmoscopy—asked to examine the left eye of a young patient—the media was clear with distant direct ophthalmoscopy—near direct examination showed normal disc and retinal vessels at the post pole, entire macula revealed plenty of yellowish lesions involving the fovea in the deeper retinal plane with glistening retinal surface,??associated focal serous detachment which needs confirmation by slit-lamp biomicroscopy---asked about the diagnosis---probable Best’s / adult vitelliform dystrophy.
    Asked to examine the left eye of another patient---showed classical signs of optic disc melanocytoma—asked to write the diagram on retinal chart.
    Then asked about the different filters in direct ophth, and uses-- asked regarding Watze-Allen sign.

    Indirect Ophthalmoscopy—of left eye—optic disc normal, macula showing diffuse areas of depigmentation with central elevated yellowish white fibrous tissue with pigmentation, no evidence of serous detachment or haemorrhage, rest of the fundus being normal---Wet ARMD, disciform stage---asked to write the diagram on retinal chart---asked what will be  the expected pathology in contralateral eye—may be dursen / dryARMD / wet ARMD---what are the causes of drusen---what is the pathology of drusen and exact microscopic location of the drusen—answered.


    20 year old student—short history—vision test, 6/36 ph 6/9 in RE, 6/36 ph 6/6 in LE—cover test showed exophoria---measured IPD—ret using only spheres—wrote power cross---VA with objective refraction, 6/9 RE, 6/6 LE---best sphere—cross cylinder---duochrome test (uniocular and binocular)---1D blur test ---tested near vision with distant correction---then cover test---examiner intervened and asked to proceed with muscle balance using Maddox rod---tested for horizontal imbalance only---revealed exophoria---did not use prisms to correct—measured BVD
    Final prescription:

    -3.0 / -0.75 80 RE---6/6, N5                                              IPD—67 mm
    -3.25 / -0.25 120 LE—6/5, N5                                          BVD—12mm

    Examiner pointed about a mistake in Maddox rod testing. Then asked to leave—still 3 mts left.

    Some Tips:

    1. MCQ—Studying between the alphabets!! of Elkington text book and chua book with this excellent web is suffice to answer most of them.
    2. OSCE—some stations may be difficult, but you can compensate by doing other stations well. So try to be expert in some of them and keep them as trump card. Ocular motility is always unpredictable. Answer meticulously covering ‘all the points’ for the questions even if u fail to demonstrate the signs.
    3. Carry your own instruments, esp trial frame, direct ophthal, retinoscope, indirect lenses. Set up the instrument before examining the patient like slit-lamp.
    4. OSE—describe the findings even if the diagnosis is unsure.
    5. Refraction—Practice makes you perfect. But even if u are expert, this part of the exam mainly depends on your Luck!!

    More candidate experience