Angle kappa was on the nasal pupillary border for the left eye, indicating exotropia. The Hirschberg reading was -3.00mm. To calculate the estimated deviation: - Subtract the angle kappa position (+2.00mm nasal) from the Hirschberg reading (-3.00mm) giving -5.00mm - Multiply the result (-5.00mm) by 22 (prism diopters per millimeter) giving -110 prism diopters Therefore, the estimated deviation is 110 prism diopters of left exotropia.

1. CASE
HISTORY &
PRELIMINARY
TESTS
N SHABALALA

2. WHAT IS A TENTATIVE
DIAGNOSIS?
– Provisional, Not fixed, Not certain
– Refers to one of several potential diagnoses of a patient’s illness
– Based on case history
– Developed as you postulate a number of different disease processes/possible causes
to your patient’s signs/symptoms that must be explored further
– It is included in a differential diagnosis
– There can be multiple tentative diagnoses and you need to perform all relevant tests
to confirm a diagnosis
– In essence a tentative diagnosis is a diagnosis that you suspect, that is yet to be
confirmed, however it must be supported by the history/background

3. HOW TO DEVELOP A
TENTATIVE DIAGNOSIS?
– Take into consideration the detailed objective and subjective case history
– Postulate likely causes for your patients complaint
– Require knowledge of presenting signs and symptoms of ocular
diseases/ conditions

4. EXAMPLES OF TENTATIVES
BASED ON COMMON SYMPTOMS
Visual Complaints e.g
– Blurry vx
– Dbl vx
– Photophobia
– Asthenopia
– H/A
Non Visual Complaints e.g
– Itching
– Pain
– Swelling
– Discharge
– Redness

5. CONVERGENCE
– Disjunctive movement of the eyes where the eyes synchronously adduct so that the
lines of sight intersect in front of eyes
– Assists in maintaining bifoveal single vision at any fixation distance
– It is a fusional movement that may be stimulated by volition, disparate stimulation
and accommodation
– Unlike Accommodation, the amplitude of convergence doesn’t deteriorate with age.
It may deteriorate due to a decrease in ACC Convergence
– Some convergence may reduce under certain abnormal circumstances
– Power or reserve of convergence can be increased by orthoptic exercises
– Symmetrical vs Asymmetrical convergence?

6. CONVERGENCE

7. TYPES OF CONVERGENCE
(SS)
– Voluntary
– Reflex
– Tonic Convergence
– Fusional Convergence
– Accommodative Convergence
– Proximal Convergence

8. NPC
– Point of intersection of the lines of sight of the eyes when maximum
convergence is utilized
– NPC Distance: Is the distance from the near point of convergence to the
midpoint of the line connecting the centre of rotation of the eyes
– Pxs with receeded NPC distances may have visual and ocular discomfort when
performing near point vision tasks

9. NPC

10. CLINICAL PROCEDURE
Equipment
– RAF Ruler
– Accommodative target
– 30cm Ruler
– Red lens/ R&G lens
– Penlight
Procedure
– Conducted in free space
– Patient is seated comfortably with
habitual Rx
– Ruler is held against outer cathus
– The patient is encouraged to
maintain fixation on target and
report double

11. CLINICAL PROCEDURE

12. CLINICAL PROCEDURE
Accommodative NPC
– Px to focus on dot on target and
report when line is double
– Ensure to check that line is initially
single before proceeding to
measure
– Slowly move the target along
midline, 15 degrees below eye level
until px reports to seeing double
Non-Accommodative NPC
– Shine light at bridge of nose
– Px to focus on penlight with red lens infront
of one eye
– Ensure to check the light is the same color as
the lens in each eye, and becomes a mixture
when both eyes are open
– Slowly move the penlight along midline, 15
degrees below eye level until the light breaks
into two colors, or patient no longer reports
a mixture

13. CLINICAL PROCEDURE
– When the patient reports diplopia (subjective), ensure to instruct the patient to
blink! If still reports diplopia, measure. If no diplopia after blink, continue
towards patient
– The sustained double is the break value
*If the px doesn’t report diplopia, note the fixation distance if one eye loses
fixation on the target (objective)
(The eye that maintains fixation is the dominant eye)
– Measure the subjective or objective break value then slowly move the target
away and ask px to report fusion or you see the eye regain fixation Recovery
value

14. CLINICAL PROCEDURE
– This is recorded as Break/Recovery in cm
– E.g 6cm/9cm
– Repeat a minimum of two times and take an average of those results
– When NPC is repeated 5 or more times, convergence ability significantly
decreases with symptomatic patients and minimally with asymptomatic
patients

15. CLINICAL SIGNIFICANCE/
INTERPRETATION
– Pxs with a convergence problem may express symptoms such as diplopia,
frontal headaches, decreases reading comprehension, asthenopia, fatigue when
performing near tasks
– NPC has a normal range of 6 to 10cm
– Closer than 5cm is considered to be convergence excess
– A remote/receeded NPC is suspected to have Convergence Insufficiency

16. ANOMALIES OF
CONVERGENCE
Convergence Insufficiency (CI):
– Inability to obtain or maintain adequate
convergence over a certain period of
time without undue effort
– Commonest cause of asthenopia
Convergence Excess
Convergence Spasm
Convergence Paralysis

17. VISUAL FIELD
Contains:
– Centeral or foveal which is measured by visual acuity test, contrast sensitivity and
macular function tests and concerned with Resolution, forms
– Foveal (central 3 degrees)
– Parafoveal (within 5 degrees)
– Macular (within 10 degrees)
– Central (fixation and within 30 degree circle, includes physiological blind spot)
– Peripheral which is concerned with Peripheral sensitivity , motion and light
detection (Beyond 30 degrees to outer field of vision)
– Normal visual field is reversed inverted map of corresponding retinal points

18. VISUAL FIELD
Normal monocular visual field limitations:
– 1. 60° Superiorly
– 2. 60° Nasally
– 3. 75° Inferiorly
– 4. 100° Temporally.

19. PERIMETRY
– It is making of a visual field using stimulus. Stimulus can be:
1. Moving (kinetic) determine the visual threshold along edge of visual field
2. Static in which the static object has different level of brightness.

20. CONFRONTATION TEST
– Simple preliminary test which is done for gross visual field screening
– Falls under kinetic perimetry
– Used as screening for moderate to severe visual field defects
– Un reliable in identifying Mild visual field defects
– Results are quantitative and test can be viewed as a pass fail criteria

21. CLINICAL PROCEDURE
– Prior to testing of visual field insure central vision and visual acuity is intact
– Pt faces the examiner at a dx of 1m with his/her eyes same level as examiner’s.
– You each focus on the other’s opposite eye while covering the contralateral eye
with palm of hand
– Avoid confusion by using 1,2,5 fingers
– Correct position : 2 finger side by side in front of the eye field . Incorrect
position: One finger behind the other

22. CLINICAL PROCEDURE
– Facial Amsler
– Finger Counting
– Simultaneous Finger Counting
– Simultaneous hand comparison
– Peripheral finger counting

23. CLINICAL PROCEDURE
Facial Amsler
– Checks for central scotoma
– Instruct patient to focus on Examiners nose
– Ask the pt, whilst they are focussed on your nose “is there anything that
appears to be missing on your face”

24. CLINICAL PROCEDURE
Finger Counting
– Checks for paracentral and peripheral scotoma in four quadrants
– Px instructed to focus on examiners open eye throughout this procedure
– Quickly project and retract (0,1,2 or 5) fingers in each quadrant and ask the
patient to report how many fingers they see
– Repeat twice in each quadrant, one projection paracentrally and the other more
peripherally
– Ensure px does not look at the fingers directly but maintains fixation on Ex open
eye

25. CLINICAL PROCEDURE
Simultaneous Finger Counting
– Checks for Extinction phenomenon :
(Harrington) ‘The presence of the stimulus
in the seeing field gives the impression of
“extinguishing” the test object in the non-
seeing field’
– Project (1,1 or 1,2 or 2,2) fingers in
opposition quadrants
– Instruct px to sum up the fingers projected

26. CLINICAL PROCEDURE
– Simultaneous hand comparison
– Hold up both hands with backs of palms facing the patient
– Px maintains fixation on your open eye
– Instruct px to report any difference in brightness or darkness of your hands
– Perform central, eccentric
– Hemianopsia, Altitudinal

27. KINETIC CONFRONTATION
– Monocularly, patient fixated on examiners open eye
– Target (preferably 1cm Red or Green) is moved in a flat plane midway between
the pt and examiner
– Begin from an unseen (outside of VF) to a seen position moving inwards
– Px instructed to report when they can see the target
– Process to be repeated in each of the quadrants for each eye separately

28. INTERPRETATION
– Compare patients field to examiners field, assumed the examiner has normal
field
– If pt cant see object and ex can, pt is interpreted to have visual field defect
– If defect is detected, re-examine the area and define further
– Discrepancies between the examiner’s and patient’s visual field after repetitions
should prompt further field examinations

29. CONFRONTATION
DRAWBACKS
– Early visual field defects can go unnoticed, particularly if one eye is affected
– Subjective test and misinterpretations of report may be presented if the patient
has poor compliance Paeds, geriatric pts
– Screening test, further examination required to diagnose

30. SPOT TEST 3

31. SPOT TEST 3
1. Angle Kappa was at the physiological position, Hirschberg reading is as below.
Calculate the estimated deviation
2. Angle kappa was on the nasal pupillary border for the left eye, Hirschberg
reading is as below. Calculate the estimated deviation

32. SPOT TEST 3
1. Angle Kappa was at the physiological position, Hirschberg reading is as below.
Calculate the estimated deviation
Hirschberg pos – Angle kappa
-4.00 mm-(+0.50mm)= -4.50mm
-4.50mm x 22pd= -99pd
 99 pd LSOT

33. SPOT TEST 3
2. Angle kappa was on the nasal pupillary border for the left eye, Hirschberg
reading is as below. Calculate the estimated deviation
Hirschberg pos – Angle kappa
-3.00mm – (+2.00mm) = -5.00mm
-5.00mm x 22pd = -110pd
 110 pd LSOT