Cataract · Pre-operative assessment
Cataract pre-operative assessment: the essential tests before surgery
Optical biometry with the IOL Master, corneal topography, macular OCT, endothelial cell count : Dr Moïse Tourabaly explains why a thorough pre-operative assessment shapes the success of your cataract surgery and the choice of your intraocular implant.
📍 Please note — The pre-operative assessment takes place during a consultation at the Cachan practice (94) or in Paris. The surgery itself is then performed by Dr Tourabaly at the Clinique Sainte-Geneviève (Paris 14), a facility dedicated to outpatient eye surgery.
Why is a pre-operative assessment essential before cataract surgery ?
Cataract surgery involves removing the clouded natural lens and implanting an intraocular lens (IOL) whose power must be calculated individually for each eye. The quality of the pre-operative assessment therefore determines three decisive factors : post-operative refractive accuracy, the choice of the implant best suited to your eye and lifestyle, and the detection of associated conditions that could change the visual prognosis or the surgical plan.
In a cross-sectional study of 598 patients scheduled for cataract surgery, routine pre-operative macular OCT detected an occult macular abnormality in 5.52 % of patients (idiopathic epiretinal membrane, vitreomacular traction, dry AMD) and led to a change in the surgical plan in 0.83 % of cases — even though the fundus examination had been considered normal (Alizadeh et al., Journal of Current Ophthalmology, 2021).
The pre-operative assessment also confirms your eligibility for premium implants (toric, multifocal, EDOF). Corneal astigmatism above 0.75 D, an irregular cornea, severe dry eye syndrome or macular disease can rule out certain implants and point toward a different strategy.
Optical biometry (IOL Master) : the key test for calculating your implant
Optical biometry is the central test of the pre-operative assessment. Performed without contact, painlessly and without dilation, it measures the following in just a few seconds :
- The axial length of the eye (from cornea to retina) with micrometric precision
- Keratometry (corneal curvature) across several meridians
- The anterior chamber depth and the thickness of the natural lens
- The horizontal corneal diameter (white-to-white)
These parameters are fed into the latest generation of implant power formulas (Barrett Universal II, Hill-RBF, Kane, Holladay 2, Haigis). In a prospective comparative study of 96 eyes (48 high myopes, 48 hyperopes), the Barrett Universal II formula placed 83.3 % of long eyes within ± 0.50 D of the refractive target at 3 months, while the Hoffer Q and Holladay 2 formulas proved most accurate for short eyes (Tañá-Rivero et al., Frontiers in Medicine, 2024).
For atypical eyes (high myopia, high hyperopia, prior corneal refractive surgery), we adapt the formula used and may call on additional measurements (Scheimpflug topography, tomography) to make the calculation more reliable.
Corneal topography : detecting irregularities and planning the toric implant
Corneal topography maps the shape of the cornea across several thousand points. It is essential for :
- Accurately measuring corneal astigmatism and its orientation (axis)
- Screening for subclinical keratoconus or post-LASIK ectasia, which would make a toric or multifocal implant unstable
- Planning the implantation of a custom toric implant by factoring in the astigmatism of the posterior corneal surface
- Checking the consistency between IOL Master keratometry and topography : a discrepancy flags an irregularity that needs investigation
Macular OCT : screening for retinal diseases masked by the cataract
Macular OCT (optical coherence tomography) analyzes each layer of the central retina in micrometric cross-sections. It is now recommended routinely before any cataract surgery to screen for retinal conditions that the clouded lens makes invisible on a standard fundus examination :
- Epiretinal membrane (the most common cause of occult macular abnormality)
- Vitreomacular traction
- Cystoid macular edema (particularly in diabetic patients)
- Early dry or wet AMD
- Macular or lamellar hole
Detecting one of these conditions can change the type of implant chosen (avoiding a multifocal in the case of an epiretinal membrane, for example) and warrant dedicated retinal follow-up before or after surgery.
Endothelial cell count and anterior segment examination
Specular endothelial cell counting measures the density of the corneal endothelial cells (in cells/mm²). These cells, which do not regenerate, keep the cornea transparent. A density below 1,500 cells/mm² or markedly altered cell shape raises the concern of post-operative corneal edema and may lead us to adapt the technique (phacoemulsification with reduced ultrasound energy, optimized corneal incisions, or even a combined endothelial graft if the cornea is already very fragile).
The slit-lamp biomicroscopic examination completes this assessment by evaluating : corneal transparency, anterior chamber depth, pupil dilation, the stability of the natural lens and its zonular attachments, the presence of capsular pseudoexfoliation, and the condition of the tear film.
Additional tests depending on the situation
Depending on your medical history and the findings of the initial examination, other investigations may complete the assessment :
- Visual field and optic nerve OCT in the case of associated glaucoma
- OCT angiography when a macular neovessel is suspected
- Scheimpflug topography (Pentacam) in the case of prior corneal refractive surgery (LASIK, PRK) to make the implant calculation more reliable
- Schirmer test and BUT in the case of dry eye — an unstable tear film distorts keratometry and must be optimized before biometry
- Cardiology or anesthesia work-up if indicated by your general health
How does the pre-operative assessment work at Dr Tourabaly’s practice ?
The pre-operative assessment takes place in a single consultation of around 45 to 60 minutes, at the Cachan practice (94) or in Paris. The tests are painless, non-invasive, and require no fasting.
- Medical history interview : functional impairment, ocular and general history, current medications (notably tamsulosin, which can complicate pupil dilation)
- Visual acuity measurement for distance and near, with and without correction
- Automated then subjective refraction to objectively assess the visual loss attributable to the cataract
- Optical biometry with the IOL Master (no contact, no dilation)
- Corneal topography
- Macular OCT and optic nerve OCT if indicated
- Endothelial cell count
- Pupil dilation followed by biomicroscopic examination and fundus examination
- Explanation of the results and shared choice of implant based on your lifestyle (monofocal, toric, EDOF, multifocal)
At the end of the consultation, you leave with a report, a prescription for antibiotic eye drops to start the day before surgery, and a surgery date at the Clinique Sainte-Geneviève (Paris 14).
Frequently asked questions about the cataract pre-operative assessment
Around 45 to 60 minutes, all tests included. After pupil dilation, you will not be able to drive for 3 to 4 hours : arrange for someone to accompany you or an alternative way home.
No. Optical biometry, topography, OCT and the endothelial cell count are performed without contact with the eye and without pain. Only the pupil dilation may cause a temporary sensitivity to light lasting a few hours.
Your carte vitale and supplementary health insurance, your current glasses, the list of your medications (notably alpha-blockers such as tamsulosin or Josir, and anticoagulants), and any recent ophthalmology examination reports. If you have already had refractive surgery (LASIK, PRK), also bring the operative report : it affects the implant calculation.
The consultation and pre-operative tests for a progressive cataract are covered by the French health insurance (Assurance Maladie) according to the standard tariffs. Additional fees may apply depending on your supplementary insurance contract. A detailed estimate is provided when you opt for a premium implant (toric, multifocal or EDOF), part of which remains payable by you.
The average wait is 4 to 8 weeks, the time needed to order the implant suited to your eye (notably if a toric or premium implant is chosen) and to schedule the surgery date at the Clinique Sainte-Geneviève. In very advanced cataracts with major functional impact, we can speed up the scheduling.
Biometry is operator-dependent and the calculation formulas should be applied by the surgeon who will operate on you. We therefore prefer to carry out the assessment at the practice to ensure consistency between the measurements, the implant choice and the surgical technique. OCT or topography reports performed elsewhere are useful and welcome, but do not remove the need for a new biometry.
Book an appointment for your pre-operative assessment
Dr Moïse Tourabaly sees patients in consultation in Cachan (94) and in Paris for a complete assessment with IOL Master biometry, topography, macular OCT and endothelial cell count. Personalized implant choice, surgery at the Clinique Sainte-Geneviève.
Scientific sources (PubMed)
- Alizadeh Y. et al. Macular Optical Coherence Tomography before Cataract Surgery. Journal of Current Ophthalmology, 2021;33(3):317-322. DOI: 10.4103/joco.joco_240_20
- Tañá-Rivero P. et al. Accuracy of intraoperative aberrometry versus preoperative biometry for intraocular lens power selection in short and long eyes. Frontiers in Medicine, 2024;11:1466885. DOI: 10.3389/fmed.2024.1466885
Medical disclaimer — This page is for information purposes only and does not replace a medical consultation. Every situation is unique ; indications, contraindications and outcomes vary from one patient to another. Only a complete ophthalmological examination can establish a surgical indication and select the appropriate implant. Absolute and relative contraindications should be discussed with your ophthalmologist.