Exophthalmometry

Exophthalmometry, its types, principle, procedure, indications, advantages and disadvantages, Luedde's exopthalmometer, hertel's exophthamlometer

1. Exophthalmometry Raju Kaiti, M. Optom Consultant Optometrist

2. Introduction Orbital disorders can be associated with forward protrusion or backward displacement of the eyes Proptosis (exophthalmos ): Abnormal forward protrusion of the eyeball orbital volume is fixed, thus, excess in volume will result in protrusion of the globe Orbit is made out of BONE…It does not yield to increase pressure within it Enophthalmos : abnormal posterior displacement of globe Sinking of eyeball into orbit

3. Causes of Bilateral Exophthalmos C avernous Sinus Thrombosis V ascular Anomaly O rbital Psudotumor ( N eoplasm) W agner’s granulomatosis Orbital Cellulitis Orbital I nfection O rbital I nflammation M etastatic N euroblastoma G rave’s eye disease # 1 Cause ( E ndocrine) Mnemonic for proptosis: VEIINN / COW OMG

4. Causes of Enohthalmos Orbital blow-out fracture Age related degeneration of orbital fat Progressive hemifacial atrophy

5. Causes of Pseudoexophthalmos Long axial length of the globe High axial myopia Congenital glaucoma Orbital asymmetry Congenital Traumatic Asymmetry of the palpebral fissures Lid retraction Contralateral ptosis (Horner’s syndrome, CN III palsy) Contralateral Enohthalmos Entropion or Ectropion Loss of tonus in EOMs Third nerve palsy

6. Proptosis Evaluation : Direct Observation Family album tomography (FAT) old photos View from above position of lids under the brow Detect relative position of cornea under lids

7. MEASUREMENT OF PROPTOSIS METHODS: SIGHING OVER THE BROW— patient is seated and the practitioner standing behind. Surgeon holds the patients head in such a manner that he looks straight down the nose. Then he rotates the head backward , until he can see just the apex of cornea. If he can see more of apex of cornea than the other , that eye is relatively proptosed. This method neither permits a record of exophthalmos for future reference nor as accurate as instruments.

8. Why perform Exophthalmometry? Exophthalmos appearance is not always confirmed by direct observation proptosis may be subtle pseudo-proptosis appearance may be cause by contralateral ptosis Presence of lid retraction normal asymmetry of palpebral fissure

9. Introduction Is the clinical procedure used to measure the anteroposterior position of the globe in the orbit relative to some orbital landmark, most commonly the lateral angle of the orbital rim. Other terms: “proptometry” or “ophthalmostatometry” Exophthalmos, or proptosis, is an abnormal forward displacement or protrusion of the globe within the orbit. Enohthalmos is an abnormal posterior displacement of the globe or a relative sinking of the globe posteriorly into the orbit.

10. Exophthalmometry In Exophthalmometry, a measurement of the distance between a point on the temporal orbital rim and the apex of the cornea is made. During Exophthalmometry, the patient’s gaze should be directed straight ahead in primary gaze. There are two basic types of exophthalmometers in wide use. These are the Luedde exophthalmometer and the Hertel exophthalmometer. Others: Naugle Ophthalmometer , Gormaz Ophthalmometer

11. Clinical Use Basic use is the detection, diagnosis, and monitoring of protrusion or exophthalmos or, less frequently, Enohthalmos. Can be very useful in monitoring the progression of exophthalmos to monitor the status of disorders Grave’s disease is the single most common cause of unilateral or bilateral exophthalmos. Detection and monitoring of Grave’s eye disease Differentiation of pseudoexophthalmos from true exophthalmos Differentiation of pseudoenophthalmos from true Enohthalmos

12. Common ways to determining globe position: Exophthalmometers Allows for images of corneal apex to project on a mm ruler Hertel (1905 ) Most common Luedde (1938)

13. LUEDDES Exophthalmometer LUEDDES Exophthalmometer is a simple transparent plastic scale with a groove which fits into outer bony margin of orbit , and amount of protrusion is read from scale . Consists of a clear, square plastic rod that is about a centimeter in thickness.

14. LUEDDES Exophthalmometer The rod is ruled in millimeters on both sides (minimizes parallax error), with a scale from 0 to 40 mm. The zero point of the scale is at the tapered end of the rod. The tapered end of the rod is notched to fit firmly against the lateral orbital margin, and the instrument is oriented perpendicular to the plane of the face.

15. The Luedde Transparent plastic mm ruler Notch conforms to angle of lateral orbital rim scale readings: 0mm (end of notch**) to 40mm parallax is minimized by using scale on both sides of the rod** ** Are advantages of using Luedde over a standard ophthalmic mm ruler

16. Luedde Procedure Palpate the lateral orbital rim to locate the deepest angle of the rim. Carefully place the notched end of the exophthalmometer against the deepest point orbital rim Scale should face out on the side Keep Luedde perpendicular to plane of face From the patient’s temporal side look through the exophthalmometer and sight the corneal apex Slightly adjust the position of your head to superimpose the markings on both sides of the ruler, specifically those that corresponds to the corneal apex Read the marking that i s tangent to the corneal apex Repeat the reading and record the reading in millimeter as well as the name of the instrument used, for example Luedde< 17, 18 17, 17

17. LUEDDES Exophthalmometer The examiner views the eye from the temporal side and notes the position of the corneal apex relative to the exophthalmometer scale. This instrument suffers from the same problem encountered if the examiner attempts to measure the position of the cornea with a millimeter ruler-there is no way to make sure that the ruler is held perpendicular to the facial plane and the examiner’s line of sight is parallel to the facial plane. It is not possible to simultaneously compare readings for the two eyes, as in Hertel.

18. HERTELS exophthalmometer Most commonly used The H ertel is designed such that both lateral orbital margins and corneal apices are visible to examiner in rapid succession (almost simultaneously). Normal values varies between—(10—21mm),and are symmetrical in both eyes. A difference of more than 2mm,between two eyes is considered significant.

19. The H ertel exophthalmometer uses a mirror system (Bausch and Lomb) or Prism ( Rodenstock ) that allows the examiner to measure the protrusion of each eye while facing the patient.

20. The Hertel Foot-plates (or yokes) “ grooved arc ” fit over bony temporal margin of lateral orbital rim crossbar Establish baseline to allow for biocular reading **B& L ’ s or Lombart ’ s design Lock

21. Exophthalmometry Set up Patient to look straight ahead Palpate the bony ridge locating deepest angle of the orbital rim

22. Hertel Procedure Loosen the lock (B&L or Lombart) slide mirrors or prisms along the horizontal bar to adjust footplates with corresponding lateral orbital rims Bring Hertel forward toward patient, keeping it parallel to floor with crossbar scale visible in front Position footplates against each lateral orbital rim independently Read of the cross bar scale (near BASE)

23. Hertel Procedure patient eye open widely & at your eye level Look at the mirror Take mm measurement where apex of cornea (lower) is superimposed on the mm scale (upper) corneal reflex lower mirror & mm scale upper mirror OU

24. Hertel vs. Luedde Hertel biocular reading baseline for sequential readings Luedde Strabismus Facial asymmetry Since facial asymmetry can cause measurement error in particular with Hertel, Luedde are use for those occasions

25. Recording measurement is made in mm For Hertel measurement record finding for each eye along with separation of instrument (BASE)

26. Example Hertel 17/18mm @ 100 base OD 20mm & OS 21mm @ 115 base Luedde OD,OS 17mm

27. Analysis measurements Eyes are compared… Comparative Relative Absolute

28. Interpretation Comparative serial exophthalmometry readings of the same eye are compared over time Use same instrument best to use Hertel over Luedde Base reading Commonly employed as a test on patients with Grave ’ s disease

29. Interpretation Relative comparison of readings b/t two eyes normal: </= 2mm Absolute comparison of readings to norms whites 12 to 20 mm (10-22mm ) average 15 -17mm blacks 12 to 24 mm average 2mm higher than whites

30. Exophthalmometry interpretations Age lower readings for children average 14mm b/t age 10-18 there is a 3mm increase Sex males have higher readings 1mm Posture In supine position NORMAL eyes sink back 1-3mm Grave ’ s disease patients eye are not affected by this phenomena

31. Exophthalmometry interpretations Ethnicity Blacks have higher reading 12-24mm Asian have smaller ranges 12-18mm

32. Final Note Reliability may be affected by poor fixation or convergence parallax errors (tilting instrument) minor deviations in position result in gross variations in reading Narrow base on Hertel Blepharospasm Facial bone dysformity may cause unreliable measurements due to unparallel placement of device Inter-observer variation is common problem associate with reliability

33. AFTER Exophthalmometry measurements: When to further evaluate… Difference of >/=3 mm b/t eyes Readings greater than the norm