100+ Free CLRE Practice Questions

Pass your Contact Lens Registry Examination (CLRE) exam on the first try — instant access, no signup required.

✓ No registration✓ No credit card✓ No hidden fees✓ Start practicing immediately

100+ Questions

100% Free

1 / 10

Question 1

Score: 0/0

Which layer of the tear film is responsible for preventing evaporation of the aqueous layer?

Lipid layer

Aqueous layer

Goblet cell layer

Mucin layer

to track

2026 Statistics

Key Facts: CLRE Exam

125

Multiple-Choice Questions

100 scored + pilot items

2 hrs

Time Limit

Computer-based exam

~70%

Passing Score

Scaled (Modified Angoff)

$225

Exam Fee

Non-refundable

Content Domains

Based on 2019 job analysis

12,370+

Certified Professionals

NCLE certification holders

The CLRE consists of 125 multiple-choice questions (100 scored, plus unscored pilot items) with a 2-hour time limit. It is administered year-round in four quarterly testing windows at Prometric testing centers or via remote proctoring. The exam fee is $225 (non-refundable). Candidates must be 18+ with a high school diploma or GED. After failing, you must wait 14 days before retaking; after 3 failures, a 90-day waiting period applies. Over 12,370 professionals hold NCLE certification.

Sample CLRE Practice Questions

Try these sample questions to test your CLRE exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1Which layer of the tear film is responsible for preventing evaporation of the aqueous layer?

A.Lipid layer

B.Aqueous layer

C.Goblet cell layer

D.Mucin layer

Explanation: The lipid layer is the outermost layer of the tear film, secreted primarily by the meibomian glands. Its main function is to prevent evaporation of the underlying aqueous layer. The mucin layer is the innermost layer that helps the tear film adhere to the corneal epithelium. The aqueous layer, secreted by the lacrimal gland, makes up the bulk of the tear film. Goblet cells produce mucin, not a separate layer.

2What is the average horizontal diameter of the adult cornea?

A.13.0 mm

B.11.7 mm

C.9.0 mm

D.10.5 mm

Explanation: The average horizontal diameter of the adult cornea is approximately 11.7 mm (vertical is about 10.6 mm). This measurement is important for contact lens fitting, particularly when selecting the overall diameter of a lens. A diameter of 9.0 mm is too small, 10.5 mm is close to the vertical measurement, and 13.0 mm exceeds the normal corneal diameter.

3The Bowman's layer of the cornea is significant in contact lens wear because it:

A.Is the primary source of corneal sensitivity

B.Regulates intraocular pressure

C.Serves as a barrier that does not regenerate if damaged

D.Produces aqueous humor

Explanation: Bowman's layer (also called Bowman's membrane) is a tough, acellular layer located between the epithelium and stroma of the cornea. Its significance in contact lens wear is that once damaged, it does not regenerate, instead forming scar tissue. The corneal nerves pass through this layer, but sensitivity is primarily associated with the epithelium and nerve plexus. Aqueous humor is produced by the ciliary body, and intraocular pressure regulation involves the trabecular meshwork.

4What is the primary function of the conjunctival goblet cells?

A.Produce the mucin layer of the tear film

B.Generate the aqueous component of tears

C.Secrete the lipid layer of the tear film

D.Form a protective barrier against UV light

Explanation: Conjunctival goblet cells are responsible for producing mucin (mucus), which forms the innermost layer of the tear film. Mucin helps the tear film spread evenly over the corneal surface by converting the hydrophobic epithelium to a hydrophilic surface. The lipid layer is produced by the meibomian glands, the aqueous layer by the lacrimal gland, and UV protection comes from other structures.

5Giant papillary conjunctivitis (GPC) is most commonly associated with which type of contact lens wear?

A.Rigid gas permeable lenses

B.Extended-wear soft lenses with infrequent replacement

C.Scleral lenses

D.Daily disposable soft lenses

Explanation: Giant papillary conjunctivitis (GPC) is an inflammatory condition most commonly associated with extended-wear soft contact lenses, particularly when lenses are replaced infrequently. Protein and debris deposits accumulate on the lens surface, triggering an immune response on the upper tarsal conjunctiva. Daily disposable lenses have the lowest GPC risk due to fresh lenses each day. RGP lenses have lower GPC rates than soft lenses, and scleral lenses, while possible, are less commonly associated with GPC.

6A patient with keratoconus exhibits which characteristic corneal finding?

A.Irregular cone-shaped protrusion of the cornea

B.Band-shaped degeneration at the corneal periphery

C.Uniformly steep cornea in all meridians

D.Flat central cornea with steep periphery

Explanation: Keratoconus is a progressive corneal disorder characterized by thinning and cone-shaped protrusion of the central or paracentral cornea. This creates irregular astigmatism that often cannot be fully corrected with spectacles. A flat central cornea with steep periphery describes the opposite of keratoconus. Uniformly steep cornea describes a steep-but-regular cornea, and band-shaped degeneration describes band keratopathy, a different condition.

7Which corneal layer is most responsible for maintaining corneal transparency through its regular arrangement of collagen fibrils?

A.Stroma

B.Bowman's layer

C.Epithelium

D.Descemet's membrane

Explanation: The stroma makes up approximately 90% of the corneal thickness and maintains transparency through the highly organized, regular arrangement of its collagen fibrils (lamellae). This uniform spacing, maintained by proteoglycans and controlled hydration, allows light to pass through without scattering. The epithelium provides a smooth optical surface and barrier, Bowman's layer is a protective membrane, and Descemet's membrane is the basement membrane for the endothelium.

8The endothelial pump mechanism is critical for contact lens wearers because it:

A.Maintains corneal deturgescence by removing excess fluid

B.Generates nutrients for the epithelium

C.Increases tear production during lens wear

D.Produces mucin to improve lens comfort

Explanation: The corneal endothelium maintains corneal deturgescence (relative dehydration) through an active pump mechanism (Na+/K+ ATPase) that continuously removes excess fluid from the stroma. This is critical for contact lens wearers because lenses can reduce oxygen supply to the cornea, potentially compromising endothelial function and leading to corneal edema. The endothelium does not produce tears, mucin, or nutrients for the epithelium.

9Corneal neovascularization in a contact lens wearer is most commonly caused by:

A.Excessive tear production

B.Overexposure to UV radiation

C.Chronic corneal hypoxia

D.Use of preservative-free solutions

Explanation: Corneal neovascularization (growth of blood vessels into the normally avascular cornea) in contact lens wearers is most commonly caused by chronic hypoxia (insufficient oxygen supply). Extended-wear and low-Dk/t lenses are the primary culprits. The cornea responds to hypoxia by stimulating angiogenic factors that promote blood vessel growth from the limbal vasculature. Excessive tears, UV exposure, and preservative-free solutions are not primary causes of neovascularization.

10A patient presents with small white infiltrates at the corneal periphery, minimal pain, and no epithelial defect. The most likely diagnosis is:

A.Corneal abrasion

B.Acanthamoeba keratitis

C.Microbial keratitis

D.Contact lens peripheral ulcer (CLPU)

Explanation: Contact lens peripheral ulcers (CLPUs) present as small (usually <1.5mm), white, round infiltrates at the corneal periphery with minimal pain and typically no overlying epithelial defect. They are usually a sterile inflammatory response. Microbial keratitis typically presents with a larger central infiltrate, significant pain, and epithelial defect. A corneal abrasion involves epithelial disruption with significant pain. Acanthamoeba keratitis presents with severe pain disproportionate to findings and often a ring infiltrate.

About the CLRE Exam

The CLRE is the national certification exam for contact lens technicians and fitters administered by the ABO-NCLE. It covers 8 domains including ocular anatomy, optics, instrumentation, pre-fitting assessment, diagnostic fitting, dispensing, follow-up care, and regulatory/administrative procedures.

Questions

125 scored questions

Time Limit

2 hours

Passing Score

Scaled score (~70%)

Exam Fee

$225 (ABO-NCLE (American Board of Opticianry & National Contact Lens Examiners))

CLRE Exam Content Outline

12%

Domain I: Ocular Anatomy, Physiology & Pathology

Structure and function of the eye related to contact lens wear — tear film, conjunctiva, corneal layers, lid anatomy, and common ocular conditions

13%

Domain II: Optics & Refractive Status

Optics of the eye and contact lenses — refractive errors, vertex distance, tear lens optics, and over-refraction principles

10%

Domain III: Instrumentation

Keratometry, biomicroscopy (slit lamp), corneal topography, tear film assessment, and other diagnostic instruments

15%

Domain IV: Pre-Fitting

Patient history, contraindications, lens material selection (Dk/t, modulus, water content), lens type selection, and base curve/diameter determination

11%

Domain V: Diagnostic Fitting

Fluorescein pattern evaluation, soft lens movement assessment, toric lens stabilization, over-refraction, and specialty lens fitting

20%

Domain VI: Dispensing

Wearing schedules, replacement intervals, lens care solutions, patient education, lens verification, and insertion/removal training

12%

Domain VII: Follow-Up Care

Follow-up evaluation, complication identification (GPC, neovascularization, keratitis, staining), and management protocols

Domain VIII: Regulatory & Administrative

FDA regulations, HIPAA, Fairness to Contact Lens Consumers Act, CPT coding, record keeping, and universal precautions

How to Pass the CLRE Exam

What You Need to Know

Passing score: Scaled score (~70%)
Exam length: 125 questions
Time limit: 2 hours
Exam fee: $225

Keys to Passing

Complete 500+ practice questions
Score 80%+ consistently before scheduling
Focus on highest-weighted sections
Use our AI tutor for tough concepts

CLRE Study Tips from Top Performers

1Focus on Domain VI (Dispensing) — it is the largest section at 20% of the exam, covering wearing schedules, care systems, and patient education

2Master fluorescein pattern interpretation for RGP lenses — central pooling (steep), central touch (flat), and alignment patterns

3Know the LARS rule for toric soft lens axis adjustment — Left Add, Right Subtract

4Memorize key Dk/t thresholds: 24 minimum for daily wear, 87 for extended wear (Holden-Mertz criteria)

5Understand the differences between lens types: soft, RGP, scleral, hybrid, and when each is indicated

6Study tear film anatomy and assessment techniques (TBUT, Schirmer test, phenol red thread test)

7Review FDA regulations: all contact lenses (including plano cosmetic) are medical devices requiring prescriptions

8Practice vertex distance compensation calculations for prescriptions exceeding +/- 4.00 D

Frequently Asked Questions

What is the CLRE exam?

The CLRE (Contact Lens Registry Examination) is the national certification exam administered by the ABO-NCLE (American Board of Opticianry & National Contact Lens Examiners) for contact lens technicians and fitters. Passing the CLRE earns the NCLE certification, which is required for contact lens dispensing licensure in many states. Over 12,370 professionals hold NCLE certification.

How many questions are on the CLRE exam?

The CLRE has 125 multiple-choice questions, of which 100 are scored and the remainder are unscored pilot questions being tested for future exams. You have 2 hours to complete the exam. Questions cover 8 domains: Ocular Anatomy, Optics, Instrumentation, Pre-Fitting, Diagnostic Fitting, Dispensing, Follow-Up Care, and Regulatory/Administrative.

What is the passing score for the CLRE?

The CLRE uses a scaled passing score set by the Modified Angoff Method with a panel of Subject Matter Experts. While the exact cut score is not publicly disclosed, it approximates 70% on a scaled basis. Results are provided immediately after completing the computer-based test, including performance breakdowns by domain.

What are the prerequisites for taking the CLRE?

To take the CLRE, candidates must be at least 18 years old and hold a high school diploma or GED. There are no specific education or experience requirements beyond this. The exam is open to entry-level candidates, career changers, and experienced optical professionals seeking formal certification.

How much does the CLRE cost?

The CLRE exam fee is $225, which is non-refundable once payment is submitted. If you need to transfer to a different testing window, there is a $75 transfer fee. Each retake attempt requires a new $225 registration payment. A combined NCLE Basic + Practical exam option is available for $250.

How is the CLRE administered?

The CLRE is a computer-based exam offered year-round during four quarterly testing windows (Jan-Mar, Apr-Jun, Jul-Sep, Oct-Dec) at Prometric Testing Centers nationwide. Remote proctoring via Prometric's ProProctor platform is also available, allowing you to take the exam from home with a camera, microphone, and internet connection.

What happens if I fail the CLRE?

If you fail the CLRE, you must wait 14 days before registering and paying for a retake. You have 3 attempts, after which you must wait 90 days before becoming eligible again. Each retake requires a new $225 registration payment. Your results email includes domain-level performance to guide your study.

What is the hardest domain on the CLRE?

Domain VI (Dispensing) is the largest section at 20% of the exam (20 scored questions) and covers the broadest range of topics including wearing schedules, lens care systems, patient education, and lens verification. Many candidates also find Domain I (Ocular Anatomy) and Domain V (Diagnostic Fitting) challenging due to the clinical knowledge required.

Do I need NCLE certification to fit contact lenses?

Requirements vary by state. Many states require NCLE certification (passing the CLRE) to dispense contact lenses independently. Some states require both the CLRE Basic and the NCLEP Practical exam. Check your state's optometry or opticianry board for specific licensing requirements.