The cost of laser refractive surgery and supplementary sulcus lens implantation for pseudophakic ametropia and astigmatism, the leeds experience

Refractive surprise occurs when an unintended refractive outcome is achieved. NHS cataract surgery aims to give good, best corrected visual acuity. The refractive target is normally emmetropia but may vary due to patient preference.

The NHS benchmark of 85% of patients achieving a spherical equivalent (SE) 1.00D within target acknowledges 3 in 20 eyes experience refractive surprise [1]. Refractive surprise following NHS cataract surgery is commonly managed conservatively with glasses or contact lenses. Intraocular lens (IOL) rotation may be used to address residual astigmatism with toric implants in the early postoperative period. When intolerable anisometropia, or ocular dominance change occurs patients may require surgical intervention.

The best form of treatment is prevention, this can be practiced by:

• Ocular surface optimisation prior to keratometry

• Immersion ultrasonography when optical biometry is challenging

• A constant optimisation

• Repeating biometry in extreme axial lengths (AL) (<21.2 mm, over 26.6 mm or 0.7 mm difference between eyes); and performing tomography in those with extreme corneal curvature (<41D, >47D, Δ > 2.5D or 0.9D difference between eyes) [2].

• For patients who have not had previous laser refractive surgery (LRS): [1]

  • Use Haigis or Hoffer Q if AL < 22.00 mm
  • Use Barrett Universal II if suite is available on biometry device otherwise use SRK/T if AL 22.00-26.00 mm
  • Use Haigis or SRK/T if AL > 26.00 mm

• For those who have had LRS use a relevant formula, such as the Barrett True K

• WHO checklist to ensure correct implant is used in correct eye of the correct patient

• Minimising surgically induced astigmatism (SIA)

  • Axis marking at slit lamp or use of an intraoperative toric alignment system if a toric IOL is used
  • Small (<2.8 mm) peripheral clear corneal incision
• Minimise variation in effective lens position (ELP)

  • 5–5.5 mm central capsulorrhexis
  • IOL centration so the capsulorrhexis edges overlap the optic
  • Complete viscoelastic removal

Eyes at risk of refractive surprise include: [1, 2]

• Corneas with an altered Gullstrand ratio (e.g. previous LRS, corneal ectasia or corneal graft)

• High ametropia and high astigmatism due to variability and refractive effect of ELP

• Combined or complicated surgery due to ELP and SIA

• Ocular comorbidities (e.g. corneal opacity/graft, ocular surface disease, glaucoma, no fundal view, staphyloma, previous retinal detachment or poor preop visual acuity)

IOL exchange for refractive surprise should rarely be considered when capsular fibrosis has ensued due to the significant risk of vitreous loss and poor accuracy (33.3-63.4% corrected within 1D) [3]. Although recent advances in surgical instrumentation (such as micro scissors) may offer safer surgical technique, the literature is heterogenous in nature with majority of studies examining late lens exchange. IOL exchange may still be considered for refractive surprise if it is done early before capsular fibrosis, Table 1, by an experienced surgeon. Supplementary sulcus IOL implantation (or a piggyback lens) and LRS are alternatives with higher accuracy and better safety profiles in the literature.

Table 1.

Relative/Absolute Surgical Contraindications (*ICL implantation) including but not limited to.

Supplementary IOLs	Laser refractive surgery	IOL exchange
•Glaucoma •Endothelial cell dysfunction •Previous uveitis/CMO •Iris defect •Previous posterior capsulotomy •Anterior chamber <2.8 mm* •Toric if there is a toric IOL in the bag •Capsular instability •Pregnancy/Lactation	•Active ocular (surface) disease •Corneal opacity •Endothelial cell dysfunction •Previous herpes simplex keratitis •Autoimmune disease •Corneal ectasia •Inadequate residual or uncut stromal bed •Pregnancy/Lactation	•Previous posterior capsulotomy •Capsular instability •Endothelial cell dysfunction •Capsule fibrosis •Pregnancy/Lactation •Previous CMO

Photorefractive Keratectomy (PRK) for myopic refractive surprise less than 3D achieved spherical equivalent within 1D of aim in 92% of eyes, with no loss of two lines of BCVA and a second procedure required in 4% of eyes [4]. Laser in situ keratomelusis (LASIK) has been shown to be accurate (96–100% within 1D) for the correction of refractive error −4D to +3.75D sphere and up to 4D cylinder for refractive surprise after cataract surgery in a single procedure [3, 5]. 0% loss of 2 lines of BCVA was observed using 2013 laser ablation profiles [3]. In a recent study by Semiz et al. small incisional lenticular extraction (SMILE) for refractive surprise after cataract surgery was shown to have an accuracy of 100% within 0.5D for myopia (−1.0D to −2.25D) and astigmatism (0.75D to 1.75D) with no loss of two lines of BCVA [6]. The need for treatment was not reported [6].

Sucloflex (Rayner Intraocular Lenses Ltd, East Sussex, UK) is an aspheric hydrophobic pseudophakic supplementary IOLs that correct −10 to +10D sphere and +1 to +6D of cylinder. The lens has lots of published data with up to 84% accuracy within 0.5D, and 100% within 1D in virgin and complex eyes with previous corneal pathology [7]. Rotation can occur with the toric version despite the undulating c-loop haptics. A mean maximal rotation of 17.63° and a 62% lens reposition rate are reported [7]. Additionally, McLintock et al. showed 0% loss of 2 lines of BCVA [7]. Rotational instability may be less problematic with the plate haptic 1stQ AddOn (1st Q, GmbH, Mannheim, Germany) hydrophilic supplementary IOL. Lens power ranges −10 to +10D sphere and +1 to +11D cylinder, with a mean maximal rotation of 3.2° (±3.3°) and a reposition rate of 9%. Outcome accuracy is up to 100% within 0.5D of target [8]. Again McLintock et al. showed 0% loss of 2 lines of BCVA [8]. ‘Piggyback lenses’ design improvements have prevented complications such as pigmentary dispersion, pupil block and interlenticular opacification, being reported in studies by McLintock et al. over a 3-month follow-up [7, 8].

The Evo Visian Implantable Collamer Lens (ICL) (STAAR Surgical, Monrovia, California) is a hydrophilic collamer lens with plate haptics, used as a phakic posterior chamber lens. It recently gained CE mark approval for correction of pseudophakic ametropia and astigmatism. It has a lens power range −20 to +10D spherical correction and +0.5 to +6D cylinder. Accuracy in a pseudophakic setting is up to 96.2% within 1D and, in a study with a 25-month follow-up, Alfonso et al. reported no loss of 2 lines BCVA and no complications in a mixture of pseudophakic ametropia eyes with and without keratoplasty [9]. Rotational stability as a pseudophakic supplementary IOL is yet to be reported. However, in phakic eyes maximal rotation is similar to the 1stQ AddOn in a supplementary setting. ICL lenses have to be precisely sized preoperatively, using the manufacturers calculator. Exchange rates in phakic eyes may be up to 20%. However, exchange rates are yet to be reported in pseudophakic eyes [9].

Accuracy, safety and cost (Table 2) of supplementary lenses and LRS, for the treatment of refractive surprise and pseudophakic ametropia may be similar in certain cases. However, individual unit’s costs for all procedures and accuracy of laser procedures may vary dependent on volume, distributor, and laser platform. Studies regarding lens reposition rates may not be transferrable to NHS practice as refractive aim is to solve anisometropia rather than to achieve emmetropia.

Table 2.

Costing estimates for single use consumables over £5 obtained from distributors with an estimated volume of 10 per year for supplementary lenses.

Cost	LASIK	PRK	SMILE	Sulcoflex	Sulcoflex Toric	AddOn	AddOn Toric	ICL	ICL Toric
Zeiss excimer laser gas	39.82	39.82
Zeiss femtosecond licence	147.00		264.00
18% ethanol		31.40
Sinskey hook	14.70		14.70
SMILE lenticule seperator			14.70
SMILE ridged forceps			12.60
PRK spatula		8.63
LASIK flap separator	14.70
Lens (prices from)				165	475.90	195	495	410	410
Lens tray/injector/loader						16.55	16.55	22.50	22.50
Keratome				5.10	5.10	5.10	5.10	5.10	5.10
Viscoelastic				6.56	6.56	6.56	6.56	6.56	6.56
Intracameral cefuroxime				5.25	5.25	5.25	5.25	5.25	5.25
Simcoe cannula				17.03	17.03	17.03	17.03	17.03	17.03
Total	216.22	79.85	306	198.94	509.84	245.49	545.49	466.44	466.44

Cost for very high/low spherical and large toric prescription lenses are up to 125% higher than those quoted above. If Mitomycin C is required for high PRK or LASIK correction, there is an additional cost of £138. Sulcoflex lenses are preloaded.

After considering relative contraindications (Table 1), preference of treatment should be based upon surgeon experience, access to a refractive laser and type of refractive correction required. LRS may offer a cost-effective treatment for low-moderate myopia, hyperopia, and astigmatism without the risk of multiple intraocular procedures when treating astigmatism. The Sulcoflex or AddOn lenses may be provided at a similar cost and accuracy to LRS for spherical corrections; additionally, they may be preferred to LRS for the correction of hyperopia or moderate-high spherical refractive errors. LRS may provide treatment of astigmatism at a lower cost. If a lens is used for astigmatism a plate haptic design, such as the AddOn, may avoid multiple intraocular procedures. More research in needed on the rotational stability of ICLs in pseudophakia, and the lenses’ outcomes in pseudophakic eyes that have not undergone keratoplasty. LRS may have an advantage in not adding to theatre waiting lists. However, patient numbers requiring interventional treatment vary depending on quantity and accuracy of cataract surgery in a unit and those that refer to it. Due to the lack of literature on early IOL exchange for refractive surprise the accuracy and safety of this could not be considered. A full cost analysis of the above treatments was not performed and was limited to consumables only; costings are specific to our unit, Leeds Teaching Hospitals.

Author contributions

Substantial contributions to the conception or design of the work; or the acquisition, analysis, or interpretation of data for the work; AO, RB, SA, AM, ASB, and DD. Drafting the work or revising it critically for important intellectual content; AO, RB, SA, AM, ASB, and DD. Final approval of the version to be published; AO, RB, SA, AM, ASB, and DD. Agreement to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved; AO, RB, SA, AM, ASB, and DD.

Competing interests

The authors declare no competing interests.