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Question 1

Px presents wanting to change from soft CL to RGP, what is your exam plan:

Answer 1

1. Hx: confirm no ocular conditions, recent infections/injuries
2. BC/VA > Refraction
3. Keratometry/Topography: K values, pupil/cornea size
   
   1. BOZR = 337.5/K(flat)
4. Slit: ocular health, tear film
5. Assess fit
6. Educate
7. Follow-up 1w

Question 2

Convert N5 and 40cm to snellen:

Answer 2

If N8 = 1M, N1 = 0.125M
N5 = 0.625M
40cm/0.625M = 0.4/0.625 = 6/9.375

Question 3

Clinical response to older Px for poor reading:

Answer 3

Age based table:
- From 40/45/50/55/60 > +1/1.25/1.75/2.25/2.5
- Amp norm is 5/3.25/2/0.75/0
Plus build up W/age norm in trial frame
- Provides Amp
Convert Amp to proportion of amplitude
- Reading add should allow half accom. at habitual
Using found Add, blur check with fused-cross
- -0.50 at 90, w/+2.50 fog
- reduce power until equalised

Question 4

Assessment of poor near vision:

Answer 4

Vergence:
Heterophoria: should be <2PD, more exo at near
- Cover test w/prism
NPC/A: <10, <12 (break/recovery). <10 (accomodation, decreases with age)
- Should report diplopia, otherwise suppression
Fusional reserve:
- NFV (base-in): Near (10,15,10)
- PFV (base out): Near (15,25,20)
Fixation disparity: Misalignment within panums > asthenopia
- Eso/exo: Mallet unit
Stereopsis: 40 seconds of arc or better
- Titmus Fly (3000 arcsecs), or Randot
- Convergence insuf, strabismus, amblyopia
Accommodative:
Stimulus to accom: Power needed to view object
Lag/Lead of accom: Normally a Lag of +0.5D
- Difference of accommodative power to STA
- Cross-cylinder: Horizontal lines clear > lag (needs plus lens) and vise versa
- MEM: Ret with near target
Range of accom: Distance from far to near point
Accommodative facility: 12 (mono), and 10 (Bino)
- +-2D flippers, cycle once target is cleared
- Low monocular facility is accommodative problem
- Vergence problem if mono is fine
Amplitude of accom: 18.5-(0.3*age)
- Minus lenses until near target blurs
- 1/amp is sustainable
Relative accom: NRA +2D, PRA -2.5D
- NRA: +ve lens until near target blur
- PRA: -ve lens until blur
- ^amplitude of accom > diplopia, and vise versa
- Tentative ADD is NRA - (NRA+PRA)/2
Gradient AC/A: 4:1
- Howell card
- Amount of convergence per D of accom.

Question 5

Poor near vision DDX:

Answer 5

Accom insuf: Blur/Asthenopia at near
- Low amplitude
- Cover test: Esophoria at near
- Poor facility clearance on minus lenses
Accom excess: Dist. blur after near (Latent hyperope)
- Variable VA/ret
- High amplitude
- Poor facility clearance on plus lenses
- Esophoria at near
Accom infacility: Blur/asthenopia at near, poor target switching
- Poor mono and bino facility on both lenses
Convergence insuf: Diplopia at near
- Poor NPC
- Exo at near
- Poor fusional reserve and AC/A
Convergence excess: Diplopia at near
- Eso at near
- High AC/A

Question 6

Response to ocular trauma

Answer 6

DDX:
* FB
* Chemical/Thermal
* Penetrating
* Blunt
Hx:
* Injury
* Symptoms > Pain, diplopia, discharge
* Medical history
Examination:
* VA
* Pupils > PERRLA, RAPD
* Lids > double eversion > Trichiasis/laceration
* Anterior
1. Conj. > FB/Laceration
2. Cornea > abrasion/FB/Infection
3. AC > hyphema
4. Iris > prolapse
5. Lens dislocation
* DFE (B-ultrasound of not visible) > RD/Vit haem
* IOP (if rupture not suspected)
Management:
1. Hyphema > Cortico. / cycloplegics
2. RD > Sx
3. Chemical > copious saline w/pH strips > cortico./cycloplegics
4. FBs > removal via 25 guage

Question 7

Normal measurements of ONH

Answer 7

Size 2mm
CDR < 0.5, < 0.2mm vertical asymmetry
ISNT
NRR pink
RNFL 80-110 um
PPA-A

Question 8

Normal gonio recording

Answer 8

Shaffer system:
Grade 0-4 in given quadrant > No structure > Schwalbe’s > TB > scleral spur > CB
0-4 pigmentation in quadrant

Question 9

BV conditions and what results from FV or RA would be poor

Answer 9

1. CI > PFV/PRA
2. CE/DI > NFV
3. Accom insuf / DE > PRA
4. Accom excess > NRA
5. Accom infacility > NRA/PRA
6. Presbyopia > NRA/PRA
7. CN palsy > NFV