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Indentation gonioscopy with Posner Gonioscope

In the four-mirror variety, all four mirrors point toward the iridocorneal angle. This allows physicians to quickly look at all segments of the angle without much rotation of the lens, significantly cutting down on examination time. Compared to three-mirror lenses, the four-mirror lenses have a relatively small and flat area of contact. Some physicians, especially those who are still perfecting their technique, may find that this smaller area of contact creates difficulties. Pushing too firmly on the lens can artificially open the angle. While this may be desired, as in indentation gonioscopy, it can also fool the practitioner into thinking that the angle is more open than it actually is. Makes of the four-mirror variety include the Zeiss, Volk G, Posner, and Susmann lenses. Volk’s popular G-4 series is available with a variety of options, including large and small rings to fit a variety of facial features, adjustable handles, and flanges for stability. Another difference between the three- and four-mirror lenses is the requirement of a viscous coupling solution. In general, three-mirror lenses actually create a vault over the cornea rather than coming into contact with it; as a result, they require the use of a methylcellulose viscous coupling solution such as Goniosol. This can be time consuming and may slow down the exam. In addition, the fluid can make subsequent visualization of the fundus, and other parts of the exam such as visual fields and fundus photography, difficult. However, in some cases, the benefits of the three mirror lens outweigh the cumbersome aspects of the use of a coupling solution. In addition, some manufacturers, such as Volk, are now offering designs that eliminate the need for a coupling solution altogether with their Advanced No Fluid (ANF+) contact option.

Gonioscopy with Goldmann Gonioscope

Gonioscopy describes the use of a goniolens (also known as a gonioscope) in conjunction with a slit lamp or operating microscope to gain a view of the iridocorneal angle, or the anatomical angle formed between the eye's cornea and iris. The importance of this process is in diagnosing and monitoring various eye conditions associated with glaucoma

Goldmann indirect goniolens: this truncated-cone like device utilises mirrors to reflect the light from the iridocorneal angle into the direction of the observer (as shown by the schematic diagram). In practice the image comes out roughly orthogonal to the back surface (nearer the practitioner), making observation and magnification with a slit lamp easy and reliable. The small, curved front surface does not rest on the cornea, but instead vaults over it, with lubricating fluid filling the gap. The border of the front surface rests on the sclera. While the view obtained is smaller than that of the Koeppe goniolens, it can be used with the patient sitting upright, and other mirrors within the device can be used to obtain views of other parts of the eye, such as the retina and the ora serrata.

Source: Wikipedia

Acromegaly - Points to be noted by an Ophthalmologist

A 40-year-old patient has noticed that his feet became bigger beyond his usual shoes...what do you think the causes for such condition?

the next Qs are about the main endocrinal cause for this condition? 

*Causes of enlarged foot:

1. Endocrine: Acromegaly- may be hypothyroidism(weight gain)
2. Oedema (e.g. pitting: cardiac failure- non- pitting: lymphedema)

*Acidophil tumors cause gigantism in children and acromegaly in adults. Acromegaly is caused by excessive growth hormone (GH) occurring during adult life, after epiphyseal closure and is almost invariably due to a secreting pituitary acidophil adenoma.

.

https://www.youtube.com/watch?v=RBYtojwZGGg

N.B: Be aware of the following;

1. Bitemporal hemianopia is due to chiasmal compression.

Correction: bitemporal hemianopia is due to multiple causes, one of them is chiasmal compression.

2. Chiasmal compression is due pituitary adenoma

Correction: there are many causes for chiasmal compression. Pituitary causes are one of them.

3. Chiasmal compression result in bitemporal hemianopia

Correction: chiasmal compression leads to different visual field defects . Bitemporal hemianopia is one of them.

4. Pituitary adenoma result in chiasmal compression.

Correction: it varies depend on the position of chiasm (central- pre- post fixed).

5. Pituitary adenoma is prolactinoma.

Correction: there are different types of adenoma with different manifestations.

Q: What are signs?

• Age: 4th–5th decades

• Enlargement: the head, jaw “mandible” (dental malocclusion), hands, feet, tongue and internal organs.

• Face: Coarseness of features (thick lips, exaggerated nasolabial folds, prominent supraorbital ridges).

• Skin:

Hyperhidrosis, and hirsutism in females.

seborrhoea, acne

• Complications:

osteoarthritis, carpal tunnel syndrome, neuropathy

gonadal dysfunction

cardiomyopathy, hypertension,

respiratory disease,

diabetes mellitus,

Q: What are the investigations?

The diagnosis may be confirmed by:

1. Direct: Measuring GH levels in response to an oral glucose tolerance test. Normal individuals manifest suppression of GH levels to below 2mU/L. However, in acromegaly, GH levels do not fall, and may paradoxically rise.

2. Indirect: increased IGF-1(insulin growth factor).

Q: What are the ophthalmic features of acromegaly?

• Bitemporal hemianopia and optic atrophy
• Angioid streaks
• see-saw nystagmus of Maddox

Q: What are the treatment options?

• Medical: Octreotide (Octreotide is similar to somatostatin. Somatostain is the natural antagonist of growth hormone. So, this octreotide inhibits the secretion of GH).

N.B: Octreotide is a vasoconstrictor which is used also in GI bleeding.

• Radiotherapy (external beam or by implantation of yttrium rods in the pituitary).

• Surgical: trans-sphenoidal hypophysectomy

ACCOMODATIVE CONVERGENCE TO ACCOMODATION RATIO

I. GRADIENT METHOD:

AC/A = heterophoria with minus lenses - heterophoria with plus lenses

Difference in power of lenses

e.g. 14 – (- 2) = 16 = 4:1 [normal]

2 – (- 2) 4

II. HETEROPHORIA METHOD

AC/A = IPD + (n-d)

D

IPD in cm ; n = near phoria ; d = distance phoria; D = accommodation

e.g. 6 + ( - 5 – 0) = 4:1 [normal]

2.5

ACCOMMODATIVE ESOTROPIA

Q: Child shown with ET. Age 3. What is your impression and what is the Ddx and how would you proceed?

1. Complete history
2. Complete ocular exam including dilated fundus exam and complete sensory and alignment testing.
3. Classification of Esodeviations

A) congenital / infantile (< 6 months)

1) essential esotropia (“congenital”)

2) early onset accomodative

3) Duane’s type I

4) nystagmus blocking syndrome

5) CN 6 palsy (or Moebius)

B) acquired comitant

1) accomodative ET: Refractive (high hyperopia)

2) accomodative ET: Non refractive (high ACA)

3) mixed mechanism (ACA and hyperopia)

4) decompensated accomodative

5) cyclic ET

6) divergence insufficiency/paresis ** often associated with brain pathology - scan!

7) spasm of near reflex

8) esophoria (common)

9) myasthenia gravis

C) acquired incomitant

1) LR weak (CN 6 palsy, slipped muscle)

3) MR restriction (#, TRO, postop)

D) pseudostrabismus (epicanthus folds, wide nasal bridge, negative angle kappa)

Child has +3.50 sphere OU and has a comitant ET of 25PD at D and 30PD at N

Treatment

1. Do a cyclopleigic refraction and give full
2. Treat amblopia
3. Possible outcomes after giving glasses and tx for amblyopia

Alignment/Fusion	<8PD/fusion	>10PD/NO fusion	Ortho D/ ET N
Treatment	Good result	Surgery	Bifocal

Amount of surgery for accomodative ET should be determined based average of near measurement with and without glasses to minimize undercorrection.

Outcome #1: Patient returns post surgery with 15PD of XT and has symptomatic diploplia. What is your management?

1. Reduce hyperopic correction
2. Fresnal prisms
3. Patching (short course)
4. Wait if 8 weeks consider reop

Outcome #2: Residual ET post op >10PD.

Rerefract and give full plus

Fresnel prism

Phospholine iodine

After 8 weeks consider re-op

Management consecutive ET after XT & persistent ET post ET

1. Repeat refraction. If hyperopia give it all. If plano and minimal myopia ignore.

2. Prisms aligned base out, 1/2 over each eye (Fresnel)

3. Treat amblyopia totally (it’s your fault)

4. Phospholine iodide.

5. Afeter 8 weeks and no improvement and >15 to 20_ you must reoperate

STEPS - REFRACTION

1.   Salutation/ Introduction

2.   History

1. Biodata Name,Age,sex,profession,

2. Chief Complaints with duration & onset

3. H/O (Spectacles, Contact Lenses, Night blindness, Glaucoma, DM, HTN, patching)

4. Family History (spectacles, Night Blindness, Glaucoma, DM, HTN)

§  Examination

3.   General Appearance Diffuse light exam. Of anterior segment

1. Facial symmetry

2. Head Tilt

3. Face Turn

4.   Pupil Examination

5.   Extra ocular movements

6.   Cover ,uncover, alternate cover test

7.   Visual acuity

1. Distant/Near

2. Aided/Unaided

3. WITH PIN HOLE

8.   Retinoscopy (with working distance and cycloplegic status)

9.   Subjective refraction

10.        Duochrom test

11.        Cross Cylinder   For Axis, Power, Presence of cylinder

12.        Maddox rod test (muscle balance for distance)

13.        NPA & NPC (near point of accommodation &near point of Convergence)

14.        Near correction

15.        Maddox wing test (near muscle balance)

16.        Supplementary tests (if indicated)

1. IPD/BVD

2. Vergence power RAF ruler

17.        Ophthalmoscopy

18.        Priscription

19.        Transposition of Prescription if indicated

20.        Say Thanks, good bye & shake hand.

Introduction

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Pediculosis pubis (Crab Lice)

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