Understanding Your Eye Exams: AAK Staging and Foveal Grading
At a Glance
Doctors use specific grading systems to track isolated aniridia in children. Lagali Staging measures corneal clouding (AAK), while Thomas Grading uses OCT scans to assess foveal hypoplasia in the retina. Knowing these grades helps predict visual potential and guide treatment options.
To provide the best care for your child, doctors use standardized grading systems to track the health of different parts of the eye. These systems act as a “roadmap,” allowing your medical team to monitor progression and set realistic expectations for your child’s vision.
The two most important systems focus on the cornea (the front window) and the fovea (the center of the retina at the back).
The Cornea: Lagali Staging (AAK)
As discussed previously, Aniridia-Associated Keratopathy (AAK) is a progressive condition where the cornea may become cloudy [1]. Doctors use the Lagali Staging System to categorize how far this process has advanced [2].
- Stage 0: The cornea is perfectly clear and healthy [2].
- Stage 1: Tiny blood vessels start to move from the white of the eye onto the edge of the cornea (less than 1mm) [2].
- Stage 2: The blood vessels move further in, but the center 2–3mm of the cornea remains clear [2].
- Stage 3: The blood vessels and cloudiness reach the very center of the cornea [2].
- Stage 4: The entire cornea is opaque (cloudy) and uneven, which significantly limits vision [2].
Why it matters: Most children begin at Stage 0 or 1. Tracking these stages helps doctors decide when to transition from simple treatments, like preservative-free lubricating drops, to advanced options like biologic drops or stem cell transplants [3][2].
The Retina: Thomas Grading (Foveal Hypoplasia)
The fovea is the part of the retina responsible for sharp, detailed vision. In aniridia, the fovea is often underdeveloped (foveal hypoplasia). Doctors use a specialized camera called OCT (Optical Coherence Tomography) to take a high-resolution “cross-section” of the retina [4][5].
How is this done on a baby? You might wonder how a squirming newborn can undergo such a precise scan without anxiety. In infants, specialists often use a handheld OCT device while the baby is swaddled in your arms, or they may perform the scan quickly under mild sedation during a more comprehensive eye examination in the operating room.
Using these OCT images, they assign a Thomas Grade from 1 to 4 [5][6]:
| Grade | What the OCT Shows | Impact on Vision |
|---|---|---|
| Grade 1 | A shallow pit is present; the light-sensing cells are well-developed [4]. | Usually correlates with the best visual potential [4]. |
| Grade 2 | The pit is almost flat, but the cells are still lengthening [4]. | Good to moderate visual potential [4]. |
| Grade 3 | No pit is visible, but the light-sensing cells still show “lengthening” [4]. | Moderate visual potential [4]. |
| Grade 4 | No pit and no lengthening of cells (sometimes called “fovea plana”) [4][7]. | Often correlates with lower visual acuity [4][5]. |
A Key Term: Outer Segment Lengthening
When you look at an OCT report, you may see the phrase outer segment lengthening. This refers to the growth of the light-sensing cells (photoreceptors) in the retina [4]. If this lengthening is present—even if the foveal pit is missing—it is a very positive sign that the eye has the biological “hardware” for functional vision [4][6].
Why These Grades Empower You
Knowing your child’s “numbers” (e.g., Lagali Stage 1, Thomas Grade 2) transforms a vague diagnosis into a clear clinical picture. It allows you to:
- Monitor Progress: You can objectively see if a stage has changed over the years [2].
- Plan Support: If you know your child has a higher Thomas Grade (3 or 4), you can advocate for early low-vision support and classroom accommodations [4].
- Coordinate Care: These grades are the universal language shared by your ophthalmologist, geneticist, and vision specialists [2][4].
Common questions in this guide
What is the Lagali Staging system for aniridia?
How do doctors check a baby's retina for foveal hypoplasia?
What does outer segment lengthening mean on an OCT report?
What does a Thomas Grade mean for my child's vision?
When do doctors start treating aniridia-associated keratopathy?
Questions to Ask Your Doctor
Curated prompts to bring to your next appointment.
- 1.Based on the most recent OCT scan, what is my child’s Thomas Grade for foveal hypoplasia?
- 2.Does my child have 'outer segment lengthening' in their retina, and what does that mean for their vision potential?
- 3.What is my child's current Lagali Stage for their cornea, and has there been any change since the last exam?
- 4.At what Lagali Stage would you consider moving from preservative-free drops to more advanced therapies like PRGF?
- 5.Can we get a copy of the OCT imaging and the exam notes that mention these specific grades?
Questions For You
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References
References (7)
- 1
[Glaucoma in PAX6-related congenital aniridia: A review of the literature].
Bastelica P, Daruich A, Paganelli B, et al.
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PMID: 39368260 - 2
[Staging of aniridia-associated keratopathy].
Náray A, Fries FN, Csidey M, et al.
Orvosi hetilap 2023; (164(27)):1063-1069 doi:10.1556/650.2023.32803.
PMID: 37422887 - 3
Management of Congenital Aniridia-Associated Keratopathy: Long-Term Outcomes from a Tertiary Referral Center.
Yazdanpanah G, Bohm KJ, Hassan OM, et al.
American journal of ophthalmology 2020; (210()):8-18 doi:10.1016/j.ajo.2019.11.003.
PMID: 31730836 - 4
Spectral-domain optical coherence tomography foveal morphology as a prognostic factor for vision performance in congenital aniridia.
Casas-Llera P, Siverio A, Esquivel G, et al.
European journal of ophthalmology 2020; (30(1)):58-65 doi:10.1177/1120672118818352.
PMID: 30556423 - 5
[Role of SD-OCT in the diagnosis and prognosis of macular hypoplasia in nystagmus patients].
Bouraoui R, Bouladi M, Nefaa F, et al.
Journal francais d'ophtalmologie 2016; (39(3)):272-6.
PMID: 26995079 - 6
Normal and abnormal foveal development.
Thomas MG, Papageorgiou E, Kuht HJ, Gottlob I
The British journal of ophthalmology 2022; (106(5)):593-599 doi:10.1136/bjophthalmol-2020-316348.
PMID: 33148537 - 7
Handheld Optical Coherence Tomography in a Young Infant With Albinism and Fovea Plana.
Rufai SR, Lee H, Gottlob I
Journal of neuro-ophthalmology : the official journal of the North American Neuro-Ophthalmology Society 2021; (41(2)):e200-e201 doi:10.1097/WNO.0000000000001094.
PMID: 32956229
This page explains eye exam grading systems for isolated aniridia for educational purposes only. Always consult your pediatric ophthalmologist to interpret your child's specific eye exam results.
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