It contains Examination Protocol for Contact Lenses along with information about pre-requisites for fitting a Contact Lens. A helpful guide for all Students, Eye Care Practitioners (Optometrist, Ophthalmologist).

1. Puneet
Mishti
EXAMINATION
PROTOCOL FOR
CONTACT LENSES
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2. CONTRIBUTORS
 PUNEET
B.OPTOM ( AMITY UNIVERSITY, GURGAON)
Clinical Intern (AHOOJA EYE & DENTAL INSTITUTE, GURGAON)
Email : Puneetj31@gmail.com
 MISHTI
M.OPTOM (CHITKARA UNIVERSITY,PUNJAB)
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3. CONTENTS
 WHYA STANDARD PROTOCOL FOR CONTACT LENSES?
 PATIENT SCREENING
 ANTERIOR SEGMENT EXAMINATION
 MEASUREMENTS OF OCULAR DIMENSIONS
 TEAR ASSESSMENT
 SPECTACLE REFRACTION
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4. Why a Standard Protocol for Contact
Lenses?
 To find out whether the patient is suitable for Contact Lenses.
 To collect the baseline information.
 To advice the best option for the patient.
 To eliminate post fitting Complications.
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5. PATIENT SCREENING
 HISTORY TAKING
- Reveals the Ocular status of Patient.
- Helps in recommending suitable lens as per Occupational Needs of patient.
- Get to know about patient’s Previous Contact lens history ,If any.
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6. PATIENT SCREENING
 Identify Why the Patient needs Contact Lenses?
- Cosmetic Purpose
- Therapeutic Purpose
- Occupational Requirements
- Pathological Condition
- Myopia Control
It will help in choosing the Best Contact Lenses for Patient.
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7. ANTERIOR SEGMENT
EXAMINATION
 Slit Lamp Biomicroscopy is used for examining the Anterior Segment of
Eye.
 Biomicroscopy is necessary as it helps in diagnosing any anomalies
present that may cause Complications in Contact Lens wear.
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8. ANTERIOR SEGMENT
EXAMINATION
 Slit Lamp Biomicroscopy is performed before any trial lens fitting to
identify possible contra-indications.
 It is repeated during and after the trial fitting to assess the fit and detect any
anterior segment changes induced by the lenses.
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9. ANTERIOR SEGMENT
EXAMINATION
A Slit Lamp Examination is performed to assess the condition of:
 Eyelids
 Conjunctiva
 Tears
 Cornea
 Anterior chamber
 Iris and lens
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10. MEASUREMENTS OF OCULAR
DIMENSIONS
 CORNEAL CURVATURE
- Keratometry ( Central & Peripheral)
- Corneal Topography
- Magnitude of Corneal and Internal Astigmatism
- Horizontal Visible Iris Diameter (HVID)
- Vertical Visible Iris Diameter (VVID)
 PUPIL MEASUREMENTS
- Under Low Illumination
- Under Standard Room Illumination
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11. MEASUREMENTS OF OCULAR
DIMENSIONS
 LID TENSION:
-Swarbrick & Holden (1996) measured lid tension by:
1. Asking the patient to look down;
2. Pulling the upper lid outward by grasping the Eyelashes gently
3. Subjectively grading the resistance to pulling
from +3 (very tight) to –3 (very loose)
Lid Tension affects lens centration and movement. Higher lid tensions cause
greater lens displacement on blinking.
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12. MEASUREMENTS OF OCULAR
DIMENSIONS
 BLINK RATE
- An adequate blink rate is necessary to prevent desiccation of the ocular
surface.
- Partial blinking may result in superficial punctate staining of the cornea.
- An average blink rate of approximately seven blinks per minute is
considered normal.
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13. TEAR ASSESSMENT
 It is performed to assess the proper functioning of Lacrimal System.
 Patients with DRY EYE are not Suitable Contact Lens Candidates.
 Tear Assessment Techniques:
- Invasive
- Non- Invasive
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14. TEAR ASSESSMENT
 Invasive:
- Break-Up-Time (BUT)
- Schirmer test
- Phenol-red thread test
- Rose bengal staining
 Non invasive:
- Non-invasive Tear Break-Up-Time (NIBUT)
- Tear prism height
- Lipid layer evaluation
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15. SPECTACLE REFRACTION
 Baseline refraction:
- Vertex distance
- Accommodation
- Convergence
 Subjective vs objective refraction
 Over-refraction
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16. SPECTACLE REFRACTION
 Baseline refraction:
It includes both subjective and objective findings (autorefractor,
retinoscopy).
 Vertex distance :
The spectacle plane is approximately 12 - 15 mm from the corneal apex. A
myope requires less minus power at the cornea than at the spectacle plane,
whereas the hyperope requires more plus power than spectacles.
 Accommodation and Convergence:
Myopes have to converge and accommodate more in wearing contact
lenses than in spectacles.
Conversely, hyperopes have to accommodate and converge less when
wearing contact lenses.
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17. Let’s Summarise!
 PATIENT SCREENING - Find out whether the person is suitable for
Contact Lenses or not.
 ANTERIOR SEGMENT EXAMINATION – Using a Slit Lamp, Check for
any anomalies in Ocular Structures of Patient, to avoid Complications.
 MEASUREMENTS OF OCULAR DIMENSIONS – Record and assess
the Corneal Curvature, Lid Tension, Pupil Measurements and Blink rate.
 TEAR ASSESSMENT – It is important to perform as it helps in knowing
the status of lacrimal system, and identifying the Suitable CL candidate.
 SPECTACLE REFRACTION – Baseline Refraction including vertex
distance etc. is required for getting adequate Vision through Contact
Lenses.
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18. REFERENCES
▪ Clinical Manual of Contact Lenses by Edward S. Bennett, Henry
▪ The IACLE Module 4
▪ The IACLE Module 3
▪ The Contact Lens Manual by Andrew Gasson, Judith Morris.
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19. THANK YOU
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