Refractive Surprise After Cataract Surgery

✅ Medically reviewed by Dr Sharon Heng

One of the risks of cataract surgery is refractive surprise, so what exactly is refractive surprise?

Cataract is the clouding of the lens. Symptoms of cataracts include gradual and progressive painless blurring of vision. Treatment will be cataract surgery or phacoemulsification where the clouded lenses will be removed and replaced with a new plastic intraocular lens.  

One of the goals of cataract surgery is to correct the refraction of the eye, negating the need for spectacles.  In some instances, the surgical outcome does not align with the patient's expectations and the refractive outcome may deviate from the planned or expected refraction - we call this refractive surprise.

In general, cataract surgery has a high success rate, despite this, there is always a risk of surprise. Therefore, it is very important for patients to have an understanding of potential outcomes and their individual risks profile, and manage their expectations accordingly.

What are some of the risk factors that predispose a patient to refractive surprise?

Inaccurate Measurements of Axial Length

One of the primary causes of refractive surprise is inaccurate measurements of the eye’s axial length, which is used to calculate the power of the intraocular lens (IOL). If the measurements are not precise, it can result in a miscalculation of the IOL power, leading to refractive surprise. Biometry calculations are most accurate in patients with average eye length and prediction errors tend to occur in very long or very short eyes (hyperopia or myopia).

Corneal Irregularities and Pre-Existing Eye Conditions

Some known risk groups with difficult IOL calculation and refractive surprise include  patients with previous laser in situ keratomileusis (LASIK), photorefractive keratectomy (PRK), radial keratotomy (RK) and patients with keratoconus due to corneal surface irregularity.

Corneal irregularities, such as astigmatism, can also contribute to refractive surprise, as they can affect the accuracy of the IOL power calculation. Additionally, pre-existing eye conditions, such as macular degeneration, diabetic retinopathy, and glaucoma, can affect the overall outcome of cataract surgery and increase the risk of refractive surprise.

Patients with High Degrees of Myopia or Hyperopia (overly short or long sighted)

Patients with high degrees of myopia or hyperopia are at higher risks of refractive surprise. In our consultation, Ms Heng evaluates the eyes in full detail and discusses individualised risks profile of the patients before recommendation of surgery, suitability of the type of intraocular lenses and what to expect following surgery.

What are the Symptoms of Refractive Surprise?

Different patients may experience different symptoms in association with refractive surprise. Some common symptoms include blurred vision or difficulty focusing.  Patients may feel that their post op vision has decreased and are overall dissatisfied with their post operative vision. 

To diagnose refractive surprise, a comprehensive ophthalmic examination will be conducted which will include visual acuity and refraction measurement, +/- corneal topography. These tests help to determine the extent of deviation from the intended outcome and identify potential underlying causes, such as corneal irregularities or IOL miscalculations. There are treatments which can correct refractive surprise.

What are Treatment Options for Refractive Surprise?

Refractive surprise may be treated conservatively or through surgical intervention. Conservative treatment includes use of contact lenses or spectacles. Surgical options include:

Refractive surgery

One option following refractive surprise is to undergo a secondary corneal based procedure, such as LASIK or PRK. This aims to correct the refractive error and improve visual acuity by reshaping the cornea to adjust the focus of the eye.

Lens exchange or piggy back intraocular lenses

Another surgical treatment option is to exchange the intraocular lens for a different power by removing the original IOL and replacing it with another lens to achieve the desired outcome. 

The risk of this is dependent on how long the lens has been implanted. There will be risks of surgery during the removal of the lens, including rupture of the capsular bag and zonular damage. This will require careful consideration by both surgeon and patient.

In some cases, a piggyback IOL may be implanted alongside the original IOL to achieve the desired refractive correction. The piggyback technique involves the implantation of two IOLs in the posterior chamber of the same eye and negates the need to remove the original intraocular lens.

Piggyback IOLs have been reported to be more accurate than IOL exchange . Another advantage of a piggyback IOL is its reversibility.

Managing Patient Expectations

It is important for patients to have a realistic understanding of the potential outcomes. There will always be a risk of experiencing refractive surprise despite the best of efforts between patient and surgeon.  

To mitigate any risks of refractive surprise, Ms Heng and her team optimises the biometry calculations through cross checking with different advanced formulae to ascertain the most accurate lenses.  

A careful consultation especially with at risk patients and to manage expectations is key to managing potential complications or unexpected outcomes despite a successful surgery. We encourage patients to actively ask questions and seek clarification on any aspects of their treatment plan.

For further information on cataract surgery or booking in for a consultation.

Contact us

Email: info@retina-eye.co.uk

Tel:  07886 677351