Ординатура / Офтальмология / Английские материалы / Pediatric Opthalmology_Mukherjee_2005

Congenital Horner’s Syndrome. Pupil of a child under one year should be examined in diffuse light. Dilatation of pupil requires more time due to strong constrictor. Slight difference in size is common. Difference in size is called anisocorca. Where it is important to find out which pupil is abnormal.

Large pupils are seen in congenital myopia and buphthalmos, congenital internal ophthalmoplegia is very rare. However in all cases of large pupil history of instillation of mydriatic or cycloglegic should be excluded.

5. Colour of Pupil. The pupil looks dark even in the most pigmented iris when seen with a torch. On careful examination the normal lens produces two miniature images the third and fourth Purkinje images. Absence of third and fourth are seen in an opaque membrane over the anterior lens capsule and absence of lens (aphakia). A white reflex in pupillary area is always pathological.

Causes of white reflex in pupillary area (see chapter on Len and Retinoblastom).

6. Examination of pupillary light reflex. A brisk direct and consensual light reflex denotes intact afferent and efferent neurological precortical path. A child with lesion of visual cortex presents as cortical blindness where the pupil are of same size and react well.

Unilateral dilated sluggish pupil with contralateral normal sized, reacting briskly to direct and indirect light is due to iridoplegia that may be therapeutic or neurological.

Bilateral fixed dilated pupil are due to

1.Bilateral irideplegia

2.Bilateral sever optic neuropathy.

MarcusGunn pupil is seen in unilateral complete lesion of optic nerve.

7. Examination of lens. Lens of an infant is examined mainly for its transparency. Most important opacity is an opacity that covers whole of the pupil but may have clear periphery hence all lenses with central opacity should be examined with full mydriasis for possibility of clear periphery because management of opacity extending beyond fully dilated pupil is urgent lensectomy with management of aphakia and avoidance of ambloypia. A lens with clear periphery may be left with dilated pupil, this allows sufficient light rays to reach the macula for its development and prevention of amblyopia.

Sub luxation and dislocation of lens is less common under one year and when present becomes obvious only on maximum pupillary dilatation.

Scattered cortical opacities do not cause visual impairment and their presence should be noted in examination card and parents informed about their non progressive nature with instruction for yearly follow up.

8. Examination of vitreous. Vitreous is examined for presence of P.H.P.V., remnants of hyoid system, vitreous haemorrhage, familial exudative vitreo retinopathy, retinopathy of prematurity. Best method to examine vitreous and rest of the fundus is by a binocular indirect ophthalmoscope using a condensing lens that give magnification, steriopsis and moderate field with maximum dilatation.

Recording of distant vision in a child. In principle and practice there is no difference in examination of vision in adults and children. The difficulty arises in reaction of the child to

method of examination, a shy child may not co-operate well to record vision, an-other child under the same circumstances may be most co-operative not only in recording of vision but also examination and manipulation of eyes. Vision is a sensory phenomenon for this co-operation of the child is most important pre requisite. Patience, practice and attention of the examiner in recording vision in a child is as important as attention of the child and co-operation of parents.

Sixty parent of afferent input to the central nervous system for development of higher centres come from vision of the child.

A child does not complain of gradual loss of vision unless it is discovered by the parents at home. A very common observation is that the child prefers to sit nearer the T.V. than others and resents being shifted away. A teacher may complain of poor attention of the child, the child may fail to copy from the black board. Most often children with poor vision are brought with squint. Unilateral loss of vision may go undetected for longer time unless the child develops squint or accidentally closes the better eye.

Acute and painful loss of vision brings a child for examination early. Recording of vision in children can be grouped into following categories.

Examination of vision of

1.New born

2.Under One year

3.Between 1-2 years

4.Between 2-3 years

5.Between 3-5 years

6.Above 5 year.

Recording of vision above five years is similar to that in adults with little modification, attention of examiner and practice. Co-operation of parents, attendants and teachers is also desired for correct interpretation.

Recording of vision under one year of age has been delt with earlier.

Recording of vision between 1-2 years of age

Recording of vision under two years is slightly easier than under one year.

Presence of squint, nystagmus, indicate poor vision at least is one eye. Nystagmus denotes bilateral diminished vision. Presence of unilateral squint invariably means diminished vision in the squinting eye. Preference of fixation by one eye means diminished vision in other eye. Closure of the better eye is resented by the child who may start crying and try to remove the obstruction. A child with searching movement most probably does not have vision in either eye. Various methods to examine distant vision are17,18,19 :

1.Optokinetic drum of Harcourt.

2.Catford drum

3.Preferential looking test.

4.Visually evoked potential

5.Teller acuity card

6.OKNOVIS17

7.Boeck candy bead test

8.Cardiff acuity card.

None of the above tests is accurate, some times more than one test has to be used. Rarely children as young as 18 months have responded to Snellen’s optotypes10

Optokinetic drum test, preferential looking test and visually evoked potential and their modifications are time honoured tests. Some new tests have been evolved for better results. They are broadly divided into two groups:

1.That depend upon the preferential looking

2.That does not depend upon preferential looking.

The principle of these test are similar to optokinetic drum. Where alternate black and white strips evoke nystagmus when the drum is activated in front of the child’s eye from a close quarter.

(a) Catford drum test In this test cylindrical drum is replaced by a circular disc with dots ranging between 0.5 to 15mm in diameter representing vision between 6/6 and 2/60. Rotation of the disc at a distance of 60 cm evokes pendular movement and not nystagmus as seen in O.K.T. The smallest target that starts the pendulular oscillation gives the vision it may over estimate vision many folds and can not be used in ambloyopia screening.

(b) Teller acuity card10, 17, 18. This test is modification of preferential looking test. This test takes less time and simple to perform. Testing distance varies with age of the child being tested infants under six month are tested at 36cm while those up to three years are examined at 55cm. The results are obtained in cycles which can be converted to Snellen’s equivalent.

(c) OKNOVIS17 This new technique is based on the principle of arresting an elicited optokinetic nyslagmus by introducing optotypes of various sizes. The instrument is a hand held revolving drum that rotates at speed of 12 revolutions per minutes. The test is done at 60cm to elicit optokinetic nystagmus, coloured pictures on the revolving drum are used. Once nystagmus is elicited optotypes of different sizes are introduced to arrest nystagmus. The test gives a rough estimate of vision.

(d) Cardiff acuity cards7. The test depends upon preferential fixation and consists of a series cards depending on principle of vanishing optotypes.

The tests that do not depend upon preferential looking

(a) Boeck candy bead test. The child identifies an incentive i.e. candy beads of gradually decreasing size at 40cm. The child’s hand is guided to locate the candy and then to mouth. This the child finds interesting and worth repeating.

(b) Other tests used are : Marble game test, Worth ivory ball test, Sheridan ball test.

Recording of vision between 2 to 3 years age

By this age the child is verbal has better power of expression some may be conversant with alphabets and numbers. Hence preferential looking test are no more required but in cases of gross visual loss or suspected absence of vision, visual evoked potentials may be required.

Commonly used methods are various types of optotypes that may be

1.Snellen’s chart

2.Landolts broken C

3.STYCAR Test (Snellen’s test for young children and retarded)

4.HOTV Test

5.Dot visual acuity test

6.Coin test

7.Miniature toy test.

The last three tests are crude tests and meant for children in second year, by three years the child can recognise shapes hence can be tested on optotypes.

Recording of vision between 3 to 5 years

By three years most of the urban children start going to some types of schools that teach them alphabets, numbers, recognise shape, dimension and colour. Rural children in developing countries who constitute 80% of paediatric population are difficult to evaluate visually due to illiteracy. Examiner may have to revert to methods employed to examine children between two to three years in these rural children.

Commonly used methods are : All the test objects are various types of optotypes, the target of which makes an angle of 5 minutes when kept of 6 meters or 20 feet the testing may be done at 3 meters with proportionally reduced size of the optotypes.

Commonly used optotypes are :

1.Snellen’s chart commonly used is in English but may be in vernacular as well.

2.Snellen’s E chart

3.Snellen’s tumbling E test

4.Landots broken C

5.Sjogren Hand or Arrow

6.HOTV test

(a) Lipman 4 letters ( It consists of four letters HOTV arranged in a circle)

(b) Sneridan 5 letters. X is added to HOTV. Addition of A and U make it seven letters, they can be used at 6mts or three meters with a mirror.

There should be no difficulty in recording vision in a child if he is literate, he can be tested on usual Snellen’s chart at six meters. But a non literate child has to be tested on other charts. It is better to have a smaller hand held version of the test type to be shown to the child at usual reading distance and explain the child, what he is expected to tell. After two or three trials the child is able to correctly tell the position of break in Landolts chart and direction of open end of E.

While recording of vision following steps are useful to gain the confidence of the child and his co-operation.

1. Record vision in normally lighted room.

2.Allow one of the parents or grand parents, preferably mother to be present near the child but forbid her to prompt the child.

3.First note the vision with both eyes open.

4.It is better to examine eye with better vision first and the other eye later instead of usual convention of examining the right eye first and left eye later. Because a child with gross visual loss in one eye will resent closure of better eye and may refuse to be tested.

5.Some children generally above five years of age can memorise the whole of the Snellen’s chart while sitting in the examination room in such cases it is better to ask the child to read from right to left rather then usual left to right barring of course Urdu, Arabic and some other letters.

6.While examining one eye the other eye should be occluded completely and watch that child does not peek over the occluder.

7.Keep the head of the child in primary position. A child may turn the head to see with the better eye.

Examination of near vision in children. Children under fifteen have strong accommodation hence their near vision is good and rarely complain of diminished vision children with high uncorrected hypermetropia may complain of asthenopia and running of letters.

If a child complains of diminished near vision the first test is to exclude hypermetropia by cycloplegic refraction. Other causes of diminished near vision are

1.Incorrectable distant vision

2.Nystagmus

3.Cycloplegia

(a) Neurological-internal ophthalmoplegia

(b) Drug induced cycloplegia

4.Malingering.

Examination of colour vision. About 8% of boys suffer from some degree of colour defect which is congenital hence it is very important to note colour vision in boys more for future planning of their career than done for any clinical purpose

Examination of field. It is very difficult to elicit field defect under 10 years of age. After 15 years of age the field examination is done as in adults. Between 10-15 years automatic perimeters may be helpful.

REFERENCES

1.Boger W.P and Peterson R.A. ; Paediatric Ophthalmology in Manual of Ocular Diagnosis and Therapy, edited by Deborah Pavan langston, third edition p-251-255, Little Brown.

2.Shaffer D.B.; Normal eye in infancy and childhood in Text book of ophthalmology, edited by Scheie H.G. and Albert D.M., 9th edition p-279-280, W.B. Saunders Company,

Philadelphia 1977.

3.Vaughan D., Asbury T.; Special subjects of paediatric interest in General ophthalmology, 10th edition p-279-285, Lange Medical Publication Singapore 1983.

4.Hoyt. C.S. Nickel BL, Billson F.A.; Ophthalmologic examination of the infant, survophth 26 : 177-189, 1983.

5.Safir A., Merker C. ; Normal eye in infancy and childhood in Text book of Ophthalmology, edited by Scheie H.G. and Albert D.M., 9th edition p-279-280, W.B. Saunders Company, Philadelphia 1977.

6.Duke Elder S. and Cook C. ; Chronology of Development in System of Ophthalmology, Vol. III part 1, p-291-312, Henry Kimpton London 1963.

7.Zwaan J.T. ; Does this baby see in Decision making in Ophthalmology, Edited by van Heuven WAJ and Zwaan J.T. p-124-125, Harcourt Brace 1992.

8.Flyon J.T. ; Evaluation of Visual Function in Neonate and Infant in Paediatric Ophthalmology Vol. I, second edition, Edited by Harley M.D. p-1-25, W B Saunders Company Philadelphia 1983.

9.Zwaan J.T. ; Uncorrectable poor vision in a child in Decision making in ophthalmology , Edited by van Heuven WAJ and Zwaan J.T. p-138-139, Harcourt Brace and Company 1992.

10.Diamond G.R. ; Evaluating Vision in preverbal and preliterate infants. In textbook of ophthalmology, Edited by Podos S.M. and Yanoff M. Vol-5, p-2.1-2.6 Mosby London 1993.

11.Goldhammer Y. ; Paradoxical pupillary reaction in Neuroophthalmology update,

Edited by smith J.L. P-39-42, Masson New York 1977.

12.Yee R.D. Balon, R.W. Hanrubia. Y. ; Study of Congenital nystagmus Br Jr. OPL 64 : 926-930, 1980.

13.Zwaan J.T. ; Cloudy cornea in neonate in Decision making in ophthalmology,

Edited by van Heuven WAJ and Zwaan J.T. p-128-129, Harcourt Brace and Company 1992.

14.Duke Elder S. ; System of ophthalmology, Vol. III, Part-II, Page 820, Henry Kimpton, London 1964.

15.Mc Dermott M.L. ; Corneal hypesthesia in Decision making in ophthalmology, edited by van Heuven WAJ and Zwaan J T P-174, Harcourt Brace and Company 1992.

16.Singh D. ; Paediatric Cataract CME series All India ophtlamological society.

17.Sharma P. ; The preliminary examination and assessment of vision in Strabismus simplified, 1st Edition p-55-62, Modern Publishers, New Delhi 1999.

18.Khurana A.K. ; Visual acuity contrast sensitivity and test for potential vision in Theory and practice of optics and refraction, first edition p-31-51 BI Churchill Livingstone Pvt. Ltd. , New Delhi 2001.

19.Ramanjit Shihota and Radhika Tandon.; Assesment of visual function in Parsons diseases of the eye. 19th edition. p-93-97. Butterworth. Heinemann Oxford 2003.

IPA in adult is 9 mm while at birth it is 8 mm. The IPA is a conch shaped space bounded by the two lids. The lids join each other laterally in acute angle and the junction is called lateral canthus. The corresponding medial junction is called medial canthus that is rounded medially. The structures in the medial canthus are caruncle, semi lunar fold and lacus lacrimalis, upper and lower puncta.

E.The caruncle represents the vestigial third lid; it does not have skin of the lid. It is a mound of conjunctiva with small hair along with their glands. It has no definite function.

F.The plica semilunaries4 is a vertical arcuate fold of conjunctiva with concavity towards the cornea. It contains some plain muscles2. The epithelium is thickened. It also contains goblet cells. This structure represents the nictitating membrane of lower vertebrates with out any function but is invariably involved in pathological process of the conjunctiva.

G.The lacus lacrimalis is a shallow depression in the conjunctival surface of the lower lid in the medial side.

H.The two lacrimal puncta initiate the lacrimal drainage. They are situated 2mm lateral to the medial canthus in the inter marginal strip, one in each lid. They are circular or oval about 1mm wide in normal eye, they are constantly in touch with the globe and initiate the lacrimal drainage.

There are two canthal ligaments, the medial and lateral.

I.The medial canthal ligament or medial canthal tendon is a horizontal fibrous structure that extends form medial canthus to the medial wall of the orbit, to this is attached medial horn of the levator and fibrous extension of the tarsal plate. It is palpable as a horizontal cord under the skin when the lateral canthus is pulled laterally. It lies anterior to the lacrimal sac. It splits into two leaves; an anterior leaf and a relatively smaller posterior leaf. The fundus of the lacrimal sac is enclosed in between these two5. The other function of the ligament is to keep the lids stretched horizontally.

J.The lateral canthal ligament is less developed than the medial, to it is attached the lateral horn of L.P.S. and lateral fibers from the tarsal plate.

THE LAYERS OF THE LID

The lid is multi-layered structure of both ecto and mesodermal origin. It is highly vascular, rich in nerve supply and lymphatic.

The layers of the lids are

A.Skin

B.Layer of muscles :

1.The orbicularis

2.levator palpebral superior

3.Muller’s muscle.

C.The fibrous layer :

1.The tarsalplate

2.The orbital septum

3.The canthal ligament’s

4.The Whitnall ligament.

D.The conjunctiva—Tarsal conjunctiva

E.Lid margin.

A.The skin of the lid is thin and delicate but rich in blood supply and sensory nerves. It is very loose; it can be lifted off the subcutaneous tissue. There is no subcutaneous fat. There are only downy hair with their glands scattered thinly throughout. Due to laxity of the skin, large amount of fluid like blood, pus and other effusion can accumulate under the skin. In fracture of paranasal sinuses, air can get under the skin causing emphysema. The Accumulation of fluid , when present is confined to the lids, only due to firm attachment of the skin to the periostium6. The skin of a newborn is tighter than adult. With age it may become loose enough to hang down at old age. The skin is thrown in horizontal lines and most prominent among them is the supratarsal fold that is used as a land mark during ptosis surgery. These horizontal lines are caused by cutaneous attachment of levator palpabral superior. They are obliterated in ptosis and edema of lid.

B.Layer of Muscles

1.The orbicularis oculi is a horizontally placed striated muscle supplied by seventh nerve. It has two parts-the orbital and the palpebral. The palpebral part spills over like a sheet in the temple, cheek and the forehead. It encircles the palpebral fissure like a sphincter and closes the lid. It is a direct antagonist of levator. The palpebral part has two smaller divisions i.e. the perceptal and pretarsal. They have their origin over the fascia of the lacrimal sac and their main function is to cause lacrimal fluid to be pumped into the nasolacrimal duct with each blink. Paralysis of orbicularis results in lagophthalmos. The orbital part surrounds the orbital margin.

2.The levator palpebral superior. This striated muscle, supplied by upper division of the third cranial nerve is the main elevator of the upper lid. Its function is to lift the upper lid and keep lifted. It is direct antagonist of orbicularis.

The muscle originates from the under surface of lesser wing of sphenoid above and in front of the optic foramen. It travels between the roof of the orbit above and superior rectus below. It reaches the lid in a wide aponeurosis that is divided in three slips.

(a) The main slip is attached to the superior border of the tarsalplate, some fibres blending with the anterior surface of tarsal plate.

(b) Some fibers anterior to this pass through the fibers of the orbicularis and get inserted in the skin to form horizontal skin creases.

(c) The posterior most fibers are attached to the upper fornix to give it its depth.

The lateral horn of the aponeurosis is attached to lateral orbital tubercle and lateral canthal ligament. The medial horn gets inserted in medial canthal ligament and frontomaxillary suture. Part of the aponeurosis blends with Whithnall ligament that acts as check ligament of the levator.

3. The Muller’s Muscle8. This in contrast to the levator and orbicularis is anon striated muscle. It lies under the conjunctiva as an ill defined mass 12 x 15mm that originates from under surface of levator and gets inserted on the upper border of the tarsal plate, deep in the

main aponeurosis, It is supplied by cervical sympathetic. It is an accessory elevator of lid its paralysis causes mild ptosis of upper lid. It augments the action of L.P.S. by 2mm. A similar but less developed muscle arises from the inferior rectus and gets attached to the lower border of tarsus of lower lid. Its paralysis causes elevation of the lower lid margin and the condition is called upside down ptosis.

C. The Fibrous Layer

1.The tarsal plate. Each lid has a tarsal plate or tarsus that is responsible for consistency and shape of the lid and gives contour to the lid margin. The tarsal plate along with orbiculris that is loosely attached to its anterior surface, form a strong protective layer when the lids are shut. The upper tarsal plate is larger than lower tarsus in all dimensions. It is about 30mm long; 9 to 12mm in height and 1mm thick. The tarsus are made up of fibrous tissues in which are embedded the meibomian glands that are arranged parallel to each other and have branching ducts. The meibomian glands open on the lid margin and these glands secrete an oily material that contributes maximum to the lipid layer of the tear. The upper tarsal glands are longer and have wider lumen than lower glands. The upper tarsus has about 25 glands while the lower has only 12 to 15 glands. The lower border of the upper tarsus is slightly concave. Either side of the tarsal plate is anchored to the corresponding canthal ligament. The inner surface of the tarsal plate is lined by tarsal conjunctiva. The tarsal glands are visible through the normal tarsal conjunctiva as light streaks.

2.The orbital septum. This structure is also known as palpebral fascia. It is a sheet of fibrous tissue of variable thickness. It is pierced by aponeurosis of levator in the upper lid and fibers from interior rectus in the lower lid. It originates from the periorbita of the orbital margin and gets attached to the peripheral margin of the tarsal plates. Medially it is attached posterior to the fossa for lacrimal sac and laterally to the orbital tubercle. The septum orbitale along with tarsal plate form a vertical barrier that separates the orbit from the lid. It limits the infective process to reach the lid from orbit and vice versa. It is not a very rigid structure. It is pushed posteriorly by effusion in lid and forward by same pathology behind. It ripples with movement of the globe. The septum prevents orbital fat to herniate in the lid.

3.Canthal ligaments. See above.

4.The Whitnall ligament9. This is a fibrous band that runs horizontally above the aponeurosis of levator palpebral superior from Whitnall tubercle on the zygomatic bone. It gives attachment to levator aponeurosis. It is one of the important landmarks inptosis surgery.

D. The tarsal conjunctiva

The tarsal conjunctiva lines the tarsi, form the inter marginal strip of the lid margin to the fornices in each eye. The normal tarsal conjunctiva is translucent over the tarsal plate. The meibomian glands are visible through the conjunctiva, so long it is translucent. The duct become obscure due to edema, follicle, papillae and scar in the tarsal conjunctiva. The tarsal conjunctiva cannot be lifted off the tarsus.

E. The lid margin

The lid margins form the borders of palpebral fissure. They extends from canthus to canthus in each lid are about 3 mm in thickness, its posterior border is sharp and must remain constantly in touch with the globe for proper spread and drainage of tear. The anterior border