Ophthalmology instruments for final year part 1 students in GSL medical

college

By Somu Venkatesh

Final Year Part 1

Fluorescein stain stripIt is used for biomicroscopic examination of antrerior epithelium of cornea

Fluorescein staining of cornea is carried out either using one drop of 2 % freshly prepared aqueous solution of the dye or a disposable autoclaved filter paper strip impregnated with the dye .

The are denuded of epithelium due to abarasions or corneal ulcers when stained with fluorescein appear brilliant green.When examined using cobalt blue light, the stained area appears opaque green

Other staining methods used for biomicroscopic examination of cornea are• Bengal rose stain 1%• Alcian blue dye used in keratoconjunctivitis sicca

Schirmer-1 test

• It is one of the tear film test

• It measures total tear secretio0ns

• It is performed with the help of a 5x35 mm strip of Whatman-41 filter paper which is folded 5mm from one end and kept in the lower fornix at the junction of lateral one-third and medial two-thirds.

• The patient is asked to look up and not blink or close the eyes.

• After 5 minutes wetting of the filter paper strip from the bent end is measured

• Normal values of Schirmer-1 test are more than 15mm.• Values of 5-10mm are suggestive of moderate to mild

keratocojunctivitis sicca and less than 5mm of severe keratoconjunctivitis.

• Others test for tear film test for1.Tear film break-up2.Rose Bengal staining

Worth’s four-dot test

• It is one test for grading binocular vision• Normal binocular single vision consists of 3

grades. Sensory anomalies include disturbances like

1. Binocular vision2. Eccentric fixation3. Suppresion4. Amblyopia5. Abnormal retinal correspondence6. Diplopia

In W4DT patient wears goggles with red lens in front of the right(R for R, Red for Right) and green lens in front of the left eye and views a box with four lights – one red, two green and one white

Interpretation:• In normal binocular single vision, the patient sees all

the four lights in the absence of manifest squint• In abnormal retinal correspondence (ARC) patient sees

4 lights even in the presence of a manifest squint.• In right suppression the patient sees only 3 green

lights,• In left suppression the patient sees only 2 red lights,• In alternating suppression the patient sees only 3 green

lights and 2 red lights, alternately.• In diplopia the patient sees 5 lights (2 red and 3 green).

• Other test are

1. Test for fixation

2. After-image test

3. Sensory function tests with synoptophore

4. Neutral density filter test

Maddox rod

• This is used in Maddox rod test

Maddox rod test:

In this patient is asked to fix on a point light in the center of Maddox tangent scale at a distance of 6 meters. A Maddox rod (which consists of many glass rods of red colour set together in a metallic disc) is placed in front of one eye with axis of the rod parallel to the axis of deviation

The Maddox rod converts the point light image into a line. Thus, the patient will see a point light with one eye and a red line with the other. Due to dissimilar images of the two eyes, fusion is broken and heterophoria becomes manifest. The number of Maddox tangent scale where the red line falls will be the amount of heterophoria in degrees. In the absence of Maddox tangent scale, the dissociation between the point light and red line is measured by the superimposition of the 2 images by means of prisms placed in front of one eye with apex towards the phoria

Enucleation spoon(optic nerve guide)

• It is a spoon shaped instrument with a central cleavage.

Use:

To engage the optic nerve during enucleation.

Evisceration curette

It consists of an oval or round shallow cup with blunt margins attached to a stout handle.

Use:

To curette out the intraocular contents during evisceration operation.

Lacrimal probes(Bowman’s)

These are a set of straight metal wires of varying thickness(size 0-8) with blunt rounded ends and flattened central platform.Uses:1. To probe nasolacrimal

duct in congentialblockage.

2. To identify the lacrimal sac during DCT and DCR operations.

Punctum dilator(Nettleship’s)

It has a cylindrical corrugated metal handle with a conical pointed tip.

Uses:

To dilate the punctum and canaliculus during syringing, probing, dacryocystography, DCT and DCR procedures.

Chalazion scoop

• It has a small cup with sharp margins attached to a narrow handle.

Uses:

To scoop out contents of the chalazion during incision and curettage.

IOL dialer or Sinskey hook

It is a fine but stout instrument with a bent tip. The tip engages the dialing holes of the IOL.Uses:1. It is used to dial the PMMA non-foldable IOL for proper

positioning in the capsular bag or ciliary sulcus.2. It can also be used to manipulate the nucleus in

phacoemulsification surgery.Nucleus manipulate may be in the form of nucleus rotation in the capsular bag, cracking of the nucleus and feeding of the nuclear fragments into the phaco tip.

Iris repositor

It consists of a delicate, flat, malleable, straight or bent blade with blunt edges and tip attached to a handle.

Uses:

1. To reposit the iris in the anterior chamber in any intraocular surgery.

2. To break synechiae at the pupillary margin.

Two way irrigation and aspiration cannula

It is available in various designs, commonly used are simcoe’s classical or reverse cannula.

Uses:

1. For irrigation and aspiration of the lens matter in extracapsualr cataract extraction.

2. Aspiration of hyphaema.

Wire vectis

It is a wire loop attached to a metallic handle.

Uses:

It is used to remove subluxated lens and anteriorly dislocated lens in ICCE technique and the nucleus in ECCE technique.

Chalazion clamp

It consists of 2 limbs like a forceps, which can be clamped with the help of a screw. The tip of one limb is flattened in the form of a round disc which is applied on the skin side, while the tip of the other arm has a small circular ring applied on the conjunctival side of the chalazion. However, rarely when the chalazion points towards the skin, the ring side is applied to the skin.Uses:To fix the chalazion and achieve haemostasis during the incision and curettage operation

Iris forceps

These are small and delicate forceps having fine 1x2 teeth on the inner side of the limbs. These are also available in various shapes and designs.

Uses:

These are used to catch the iris for the purpose of iridectomy during operations for cataract, glaucoma, optical iridectomy and excision for iris prolapse, tumours and entangled foreign bodies.

Kelman-McPherson forceps

These are fine forceps with bent limbs.

Uses:

1. To hold the superior haptic of IOL during its placement.

2. To tear off the anterior capsular flap in ECCE.

3. Can be used for suture tying.

de Wecker’s scissors

They are fine scissors with small blades directed at right angles to the arms. The blades are kept apart, making V-shape, by spring action.

Uses:

It is used to perform iridectomy, iridotomy and to cut the prolapsed formed vitreous and pupillary membrane.

Spring action (Barraquer’s type) needle holder

These are available in various sizes with straight or curved tips, in different shapes and may be with or without locking system. The jaws of the needle holder are finely serrated to hold the fine needles firmly.

Uses:

Spring type needle holder are used for passing sutures in the conjunctiva, cornea, sclera and extraocular muscles.

Muscle (strabismus) hook

It is similar to the lens expressor in but has a blunt guarding knob at the end to prevent muscle slippage. The plane of the handle is the same as that of the curvature of the hook.Uses:1. It is used to engage the

extraocular muscles during surgery for squint, enucleation and retinal detachment.

2. In the absence of lens expressor, it may be used in its place.

Lens expressor(hook)

It is a flat metal handle with a rounded curve at one end. Tip of the curve is knobbed. The plane of the handle is at right angle to the curvature of the hook.

Uses:

1. To apply pressure on the limbs at the 6 O’clock position during the delivery of lens in intracapsular cataract extraction with Smith’s (tumbling) and capsule forceps techniques.

2. To express the nucleus in extracapsular cataract extraction.

3. It can also be used as muscle hook if the latter is not available.

4. Also used along with wire vectis to extract out the dislocated lens.

Castroviejo calliper

It is a divider like instrument, to one arm of which is attached a graduated scale (in mm). Its other arm can be moved by a screw over the scale.Uses:It is used to take measurements during squint, ptosis, retinal detachment and pars plana vitrectomy surgery. It is also used to measure corneal diameter and visible horizontal iris diameter.

Universal metallic eye speculum

It is called universal eye speculum because it can be used for both eyes i.e., right as well as left.

It has 2 limbs and a spring mechanism with a screw to adjust the limbs.

Desmarre’s retractor

It is a saddle shaped instrument folded on itself at one end. It is available in 2 sizes:small(paediatric)and large (adult).Uses:It is used to retract the lids during examination of the eyeball in cases of blepharospasm in children, in cases with marked swelling and ecchymosis, removal of corneoscleralsutures, removal of corneal foreign body and for double eversion of upper lid to examine the superior fornix.Advantages: Allows continuous adjustment of the lids and width of the palpebral aperture.

Plane mirror retinoscope

Spherical convex lens

Spherical concave lens

Cylindrical convex lens

Cylindrical concave lens