Ординатура / Офтальмология / Английские материалы / Pickwell's Binocular Vision Anomalies 5th edition_Evans_2007

APPENDICES

Appendix 7 Treatment of amblyopia

The flow chart below is a schematic guide to the treatment of amblyopia (see Ch. 13). The values (e.g. refractive errors and ages) are approximate and other factors (e.g. motivation) should influence decisions. Orthotropic refractive amblyopia can be treated at any age (Ch. 13). If the visual acuity in anisometropia does not improve with spectacles, it might with contact lenses; otherwise patching will be required. Asymptomatic adults with anisometropic amblyopia may prefer not to receive treatment and treatment may be unnecessary unless symptoms or vocational requirements suggest otherwise. For strabismic patients over the age of about 8 years patching is usually contraindicated and any marked change in their refractive correction should be accompanied by instructions to cease wear and return if diplopia occurs. Indeed, any patient with amblyopia who is being treated should be so instructed and should be closely monitored.

Treatment of functional amblyopia

Correct any significant refractive error

18 weeks

If still amblyopic

351

APPENDICES

Appendix 8 Worksheet for the investigation of incomitancy (see Ch. 17)

MOTILITY

N.B. recorded as the patient sees it (like visual field), with their left field on the left side of the diagram

3. Diplopia:

■ In this position, the paretic eye’s image is furthest out

Conclusion: Paretic muscle(s):................................................................

Hess screen:

1.Which eye is deviated (which is strabismic in the cover test)? R / L

2.Which is the smaller plot ( paretic eye)? R / L

3.In the paretic eye’s plot, which muscle appears to be underacting the most ( paretic muscle(s))?.......................................................................

Is there overaction of the contralateral synergist? yes / no (if no,

APPENDICES

Lindblom’s method:

Patient views a 70 cm horizontal rod at 1 m. If no vertical diplopia, use two Maddox rods (with double Maddox rods, perceived tilt is in direction that affected muscle would rotate eye: 10° suggests one superior oblique muscle likely to be involved, 10° suggests bilateral).

Conclusion: Paretic muscle(s):...................................................................

Anomalous head position:

N.B. rarely, this can be paradoxical (i.e. opposite to below)

Head tilt (tipped on one side)

...........degrees [estimate], top tipped to patient’s right / left (delete as appropriate)

Right:

LSO (likely) or LSR/RIO/RIR (unlikely)

Head elevation (chin up or down)

....... ...degrees [estimate], chin: up/down [delete as appropriate]

Head turn (turn to one side)

...........degrees [estimate], nose turned to patient’s: right / left [delete as appropriate]

APPENDICES

Appendix 9 Investigation of reduced visual acuity from a suspected visual conversion reaction

Health checks : refer if abnormal

If monocular:

■Occlude with refractor head

■Polarization

■Anaglyph

■Fogging

If binocular:

■Refractive checks

●Pinhole

●Plano placebo lens

●Placebo grey lens

●cf. subjective and objective: is patient consistent?

●Comparison with opposite of preferred lens

■Other tests

●Reduce testing distance

●Forced choice preferential looking

●Kinetic perimetry: ? spiral field

●Kinetic perimetry: ‘look at the other stick’

●VEPs (? only if VAs 6/24)

355

APPENDICES

Appendix 10 Norms and formulae

Norms

The table below gives norms for orthoptic tests. These norms vary little from age 6–12 years (Jimenez et al 2004b) but values for younger children are given in Appendix 2. Values for the fusional reserves are quoted in prism dioptres and the near test distance is 40 cm. Assuming a normal distribution, 68% of the population lie within 1 standard deviation (SD) of the mean and 98% within 2 SD. Thus, the data in the table can be used to estimate exactly how abnormal are a given set of data. It should be noted that comparing a patient’s performance with the mean and standard deviation of a normal population simply informs the clinician how ‘normal’ the patient is. Being abnormal does not necessarily mean that a person requires treatment.

(continued)

356

Formulae

The formula for calculating the AC/A ratio by the heterophoria distance method is:

AC/A PD (Dist phoria Nr phoria) (Jennings 2001a)

F

where PD is interpupillary distance in cm, F is dioptric distance from distance to near. Exo-deviations are entered as negative values and eso-deviations as positive values.

The formula for converting the NPC in cm to a value for the convergent amplitude at this point in is:

10 PD 2.7 (Goss 1995 page 23) NPC

where PD is interpupillary distance in mm, NPC is near point of convergence in cm.

Prismatic effect for free-space stereograms 2.5 separation of identical points (cm)

357

Ethical declaration: The author developed the IFS exercises at the Institute of Optometry, which is a charity. The exercises are marketed by I.O.O. Sales Ltd. which exists to raise funds for the Institute of Optometry. I.O.O. Sales Ltd pays a small ‘award to inventor’ to the author based on sales of the IFS exercises.

359